Topic was published via ActivityPub on Invalid date

Software Discourse
1

This bug refers to the topic Proposal: Run SocialHub forum at activitypub.eu core domain

The Publication date of the AP message is displayed incorrectly as “Invalid”.

Snapshot of the topic that displays the invalid date
Snapshot of the topic that displays the invalid date1229×673 87 KB

The ActivityPub information dialog also shows “Invalid date” in its UI:

The ActivityPub information dialog for the topic
The ActivityPub information dialog for the topic801×459 42.3 KB

(PS. AP processing dragging forum down? by the reply of @thisismissem dragged the forum down, and the images above needed 5 retries before the upload succeeded.)