diff --git a/src/Bundle/ChillActivityBundle/Entity/Activity.php b/src/Bundle/ChillActivityBundle/Entity/Activity.php
index 2a5ae6acb..9adfa057f 100644
--- a/src/Bundle/ChillActivityBundle/Entity/Activity.php
+++ b/src/Bundle/ChillActivityBundle/Entity/Activity.php
@@ -195,7 +195,7 @@ class Activity implements AccompanyingPeriodLinkedWithSocialIssuesEntityInterfac
      * @ORM\ManyToOne(targetEntity="Chill\MainBundle\Entity\User")
      * @Groups({"docgen:read"})
      */
-    private User $user;
+    private ?User $user;
 
     /**
      * @ORM\ManyToMany(targetEntity="Chill\MainBundle\Entity\User")
@@ -494,7 +494,7 @@ class Activity implements AccompanyingPeriodLinkedWithSocialIssuesEntityInterfac
         return $this->activityType;
     }
 
-    public function getUser(): User
+    public function getUser(): ?User
     {
         return $this->user;
     }
@@ -681,14 +681,14 @@ class Activity implements AccompanyingPeriodLinkedWithSocialIssuesEntityInterfac
         return $this;
     }
 
-    public function setUser(UserInterface $user): self
+    public function setUser(?User $user): self
     {
         $this->user = $user;
 
         return $this;
     }
 
-    public function setUsers(?Collection $users): self
+    public function setUsers(Collection $users): self
     {
         $this->users = $users;
 
diff --git a/src/Bundle/ChillActivityBundle/Form/ActivityType.php b/src/Bundle/ChillActivityBundle/Form/ActivityType.php
index 6d198c5fa..5dfd756f9 100644
--- a/src/Bundle/ChillActivityBundle/Form/ActivityType.php
+++ b/src/Bundle/ChillActivityBundle/Form/ActivityType.php
@@ -225,6 +225,7 @@ class ActivityType extends AbstractType
             $builder->add('user', PickUserDynamicType::class, [
                 'label' => $activityType->getLabel('user'),
                 'required' => $activityType->isRequired('user'),
+                'multiple' => false,
             ]);
         }
 
diff --git a/src/Bundle/ChillActivityBundle/Resources/views/Activity/_list_item.html.twig b/src/Bundle/ChillActivityBundle/Resources/views/Activity/_list_item.html.twig
index 885125aa6..8d1aba2b3 100644
--- a/src/Bundle/ChillActivityBundle/Resources/views/Activity/_list_item.html.twig
+++ b/src/Bundle/ChillActivityBundle/Resources/views/Activity/_list_item.html.twig
@@ -63,7 +63,7 @@
                 </div>
             {% endif %}
 
-            {% if activity.user and t.userVisible %}
+            {% if activity.user is not null and t.userVisible %}
                 <div class="wl-row">
                     <div class="wl-col title"><h3>{{ 'Referrer'|trans }}</h3></div>
                     <div class="wl-col list">
diff --git a/src/Bundle/ChillActivityBundle/Resources/views/Activity/show.html.twig b/src/Bundle/ChillActivityBundle/Resources/views/Activity/show.html.twig
index acda43b97..fca6a7658 100644
--- a/src/Bundle/ChillActivityBundle/Resources/views/Activity/show.html.twig
+++ b/src/Bundle/ChillActivityBundle/Resources/views/Activity/show.html.twig
@@ -34,10 +34,12 @@
 
         <div class="item-row separator">
             <dl class="chill_view_data">
-                <dt class="inline">{{ 'Referrer'|trans|capitalize }}</dt>
-                <dd>
-                    <span class="badge-user">{{ entity.user|chill_entity_render_box }}</span>
-                </dd>
+                {%- if entity.user is not null %}
+                    <dt class="inline">{{ 'Referrer'|trans|capitalize }}</dt>
+                    <dd>
+                        <span class="badge-user">{{ entity.user|chill_entity_render_box }}</span>
+                    </dd>
+                {% endif %}
 
                 {%- if entity.scope -%}
                     <dt class="inline">{{ 'Scope'|trans }}</dt>
diff --git a/src/Bundle/ChillMainBundle/Resources/public/module/pick-entity/index.js b/src/Bundle/ChillMainBundle/Resources/public/module/pick-entity/index.js
index 6b143a11d..99f83e1e3 100644
--- a/src/Bundle/ChillMainBundle/Resources/public/module/pick-entity/index.js
+++ b/src/Bundle/ChillMainBundle/Resources/public/module/pick-entity/index.js
@@ -18,6 +18,7 @@ function loadDynamicPicker(element) {
             isMultiple = parseInt(el.dataset.multiple) === 1,
             uniqId = el.dataset.uniqid,
             input = element.querySelector('[data-input-uniqid="'+ el.dataset.uniqid +'"]'),
+            // the "picked" will always be an array, even if multiple is false
             picked = isMultiple ?
                 JSON.parse(input.value) : (
                     (input.value === '[]' || input.value === '') ?
@@ -54,15 +55,11 @@ function loadDynamicPicker(element) {
             },
             computed: {
               notPickedSuggested() {
-                if (this.multiple) {
-                  const pickedIds = new Set();
-                  for (const p of this.picked) {
-                    pickedIds.add(`${p.type}${p.id}`);
-                  }
-                  return this.suggested.filter(e => !pickedIds.has(`${e.type}${e.id}`))
+                const pickedIds = new Set();
+                for (const p of this.picked) {
+                  pickedIds.add(`${p.type}${p.id}`);
                 }
-
-                return this.suggested.filter(e => e.type !== this.picked.type && e.id !== e.picked.id);
+                return this.suggested.filter(e => !pickedIds.has(`${e.type}${e.id}`))
               }
             },
             methods: {
@@ -90,7 +87,11 @@ function loadDynamicPicker(element) {
                       this.suggested.push(entity);
                     }
                     this.picked = this.picked.filter(e => !(e.type === entity.type && e.id === entity.id));
-                    input.value = JSON.stringify(this.picked);
+                    if (this.multiple) {
+                      input.value = JSON.stringify(this.picked);
+                    } else {
+                      input.value = "";
+                    }
                 },
             }
         })