September - last edited September
I had to use cheats to fix this issue...as a workaround..but it fixed it for me.
I had same issue of XP bar load fully then unload, with no points given.
But with cheat, able to restore it back so XP bar loads normally when practicing magic, using magic, etc and gives Talent point
To do this:
Had to use go to Cheat Console with CTRL SHIFT C and enable cheats: Testingcheats True
Then typed: stats.set_stat rankedStatistic_WitchOccult_WitchXP 50
This would bring my level back to Neophyte Spellcaster rank and would refund my Talent points back and whatever cause the XP bar to load rapidly to return to normal.
Instead of Neophyte level (50), I could probably use 350 or 850 to other ranks and might still work.
After that, to bring back up to Virtuoso, I used: stats.set_stat rankedStatistic_WitchOccult_WitchXP 2350
To get extra Talent point, then would use: stats.set_stat rankedStatistic_WitchOccult_WitchXP 2850
But only did that once or twice as I had went through Practicing Magic and Experimenting numerous times so just getting back what I should have got.
Anyway, once it was fixed, I turned cheats off with: Testingcheats False
Turned off Cheat console with CTRL SHIFT C again
I then bought perks of ones I originally had and continued leveling up as normal.
Testing leveling up by practicing magic and experimenting and XP bar now loads up normally and when gets to the end, gives you a point and goes down.
Now I can continue playing.
Confirming here it worked for me also, on a relatively new spellcaster who got stuck at 17 perk points. He's the third spellcaster sim to bug out on me while several others have made it to filling out all their perks without issue.