Stopped receiving EXP

So, yesterday, out of boredom and desire to play as an Au Ra while not using Fantasia on my favorite blue cap lalafell boy, I've created a second character. And today, when I decided to continue MSQ and play as my main character again, I've noticed that I am no more receiving EXP.
I went to a level 80 dungeon (Amaurot, I was level 84 Summoner), and then saw that I wasn't getting any EXP for beating up enemies, and after the whole dungeon was cleared, I didn't get any EXP at all.
I thought it's because of the Au Ra guy I've made so I deleted him (he was only level 14, and I had his appearance saved already so I wasn't too upset), logged back into my lalafell dude and still didn't get any EXP from killing the enemies.

Eventually, however, I got some EXP - from killing a level 79 mob, but then it gave me 50% of EXP in place of 100% I was usually getting before.

Did my second character affect my main character somehow? Or is it somehow related to my server?

And sorry if I post this in a wrong forum theme, it's my first time using it ;w;
------
UPD:
I think I just came face to face with EXP gain halting or getting reduced/doubled depending on how big is the gap between my current job's level and the enemy's level. But I cannot help but think that I used to get EXP from level-synced dungeons before... Maybe my memory is just playing tricks on me? I just have to reassure myself here now.