Tentative: issue with new page/civiwp patch
This is a tentative issue, but I wanted to flag it while I do some more testing - just in case someone somewhere is dropping a point release tonight.
I applied the patch for turning page= into civiwp= and have had problems with forms in extensions. Our URL /civicrm/governance/proxyvote began resolving to /civicrm/governance/proxyvote?civiwp=CiviCRM. And then the form didn't process when submitted - postprocess() just didn't fire. I'm seeing similar on profile links: /civicrm/profile/create/?gid=1&reset=1 becomes /civicrm/profile/create/?gid=1&reset=1&civiwp=CiviCRM.
I think it's very likely this is something in our setup, or a silly mistake on my part somewhere. @kcristiano seems to have tested on similar setups and it's been fine. But I've tried this on two sites with the same issue. The first is running WP 5.4, Civi 5.24.6, the second WP 5.4 and 5.25. The latter has far fewer plugins or extensions, but neither are entirely clean.
I'll test more tomorrow and report back. Hopefully this is something I've done wrong / in our setup.