Any idea why a proficiency would not show up?

[subtledoctor]

I start a game in SoA to test a mod. Put four pips into a proficiency at  character creation. Game starts: they are not there. Check the savegamein NI: there are no op233 effects for that proficiency. There are for every other proficiency. Going forward in the game, if I level up I see the proficiency with no pips. I can now put pips in, and they are retained and operate perfectly normally. It's only during character generation, any pips I put there just disappear.

It's the damndest thing.

I don't even know how to troubleshoot it. There are no spells/scripts/etc. affecting that proficiency, nothing I can see in NI. It seems to be something hard-coded, or in the UI. The proficiency  choice screen properly records their selection, but when I click 'OK' and go  back to the game screen, they have disappeared.

This is on BG2EE v2.6.6. The proficiency seemed  to work fine when I tested it on BGEE 2.6.6.

I'm at a total loss here.

EDIT - uh-oh. I was using stat 134 'EXTRAPROFICIENCY20' for this skill. If I change it to use stat 109, it works fine. Does  BG2EE have a hard-coded bug preventing it from using ExtraProf20?? That would be... bad. I don't have any other free proficiencies to use!

Edited October 9, 2022 by subtledoctor

[subtledoctor]

I'm having trouble replicating this? It seems inconsistent. I have a spell being applied in the CLAB file with:

  LPF ADD_SPELL_EFFECT INT_VAR target = 1 opcode = 326 parameter1 = 1 parameter2 = %prof_134_beq% timing = 1 STR_VAR resource = ~d5cs134a~ END
  LPF ADD_SPELL_EFFECT INT_VAR target = 1 opcode = 326 parameter1 = 2 parameter2 = %prof_134_beq% timing = 1 STR_VAR resource = ~d5cs134b~ END

...so that a different effect is applied in-game depending on whether you have 1 or 2 pips in that proficiency. What I'm seeing sometimes in my testing is that, when I put two pips into the proficiency, the first conditional spell gets applied by the second one does not. And when I look at the savegame, the character has zero pips recorded in op233  effects. Which means the first conditional spell should not have been applied! So it's almost like... the proficiency is there and the spell  begins to respond to it, but then an op337 effect is removing the op233 proficiency effect. But I  have searched exhaustively and there is no spell or effect being applied with op337. And there are no scripts affecting stat 134. So it seems like some kind of internal mechanism removing the proficiency points?

I made a slimmed-down test mini-mod that only enables stat 134 as a proficiency but doesn't do anything else. And in that case it seems to stick. So maybe it is the addition of more proficiencies to the CharGen process? Maybe some kind of overflow, which causes the last stat to be lost? I tried changing around the order of rows in weapprof.2da and that didn't make a difference. So the order of stats in stats.ids seems more important.

Sigh.