I caught a level 20 Oddish a few days ago and I went to level it up once to evolve it to gloom. I didn't do any switch leveling and just threw an exp share on it. When it leveled up to 21 I was watching a video at the same time so I looked away but I'm pretty sure I saw the start of the evolution animation. When I looked back I still had an oddish and it had the message "Oddish evolved into Oddish". I neglected to take a screenshot because I assumed/hoped that if I leveled it up again it would successfully evolved. I then leveled it to 23 by exp share and still nothing. This was on a server using the latest stable Pixelmon server version. I've been evolving pokemon all morning with no issue and my server console didn't have any error messages.

Mod List:

We've had the issue a few more times with other players and it appears that if you disconnect and reconnect to the server it allows the pokemon to evolve on it's next level-up.

Hi,

The team is currently aware of the issues revolving around evolutions, and there is a master ticket with any and all info relating to evolutions. (https://www.pixelmonmod.com/tracker.php?p=2&t=14241)

We are currently working on a full fix, however, all we can suggest in the meantime are the following:
1) Leaving the game and restarting your launcher/server.
2) Or using the /evolve command (may need to ask server admins to do this if you play on a server) if the evolution criteria have been met, and it still doesn't trigger a default evolution. This wouldn't be considered cheating, since it is a bug affecting the progression, not an official game mechanic.

Thank you for filing a report. I will lock this ticket and mark it as a "researching" as there is no "duplicate" option in the support tracker and I will also add it to the master ticket.

I will reply back if any significant progress is made with fixing the bug.