I'm currently facing a weird issue with a Joomla + CiviCRM website I supervise. Since ca. version 5.50 I've noticed that some contacts (newer and older accounts) are, when trying to sign up to an event, get registered to another one. In all the confirmation emails the correct event is stated, yet in the backend they are listed of participants of another event. Another intresting detail is, while this can happen with every event one wants to register for, in such a case they always get assigned to the same event. According to the PHP error log no error occured in the time of those faulty signups.
I wonder if someone on here did face a similar issue and maybe knows how to fix it.