Sorry to be the bearer of bad news yet again but I've found another bug.
Selecting the II battlegroup ships in the doctrine screen causes a hard crash-to-desktop.
see error log below:
Spoiler
3353 1891198 [Thread-2] ERROR com.fs.starfarer.combat.CombatMain java.lang.NullPointerException: Cannot invoke "com.fs.starfarer.api.combat.ShipVariantAPI.getHullSpec()" because "curr" is null
3354 java.lang.NullPointerException: Cannot invoke "com.fs.starfarer.api.combat.ShipVariantAPI.getHullSpec()" because "curr" is null
3355 at com.fs.starfarer.api.impl.campaign.fleets.DefaultFleetInflater.inflate(DefaultFleetInflater.java:466)
3356 at com.fs.starfarer.campaign.fleet.CampaignFleet.inflateIfNeeded(Unknown Source)
3357 at com.fs.starfarer.campaign.command.J.updateSampleFleet(Unknown Source)
3358 at com.fs.starfarer.campaign.command.J.advanceImpl(Unknown Source)
3359 at com.fs.starfarer.ui.OOOo.advance(Unknown Source)
3360 at com.fs.starfarer.ui.interfacenew.advanceImpl(Unknown Source)
3361 at com.fs.starfarer.campaign.command.F.advanceImpl(Unknown Source)
3362 at com.fs.starfarer.ui.OOOo.advance(Unknown Source)
3363 at com.fs.starfarer.ui.interfacenew.advanceImpl(Unknown Source)
3364 at com.fs.starfarer.ui.newui.o0OO.advanceImpl(Unknown Source)
3365 at com.fs.starfarer.ui.OOOo.advance(Unknown Source)
3366 at com.fs.starfarer.ui.interfacenew.advanceImpl(Unknown Source)
3367 at com.fs.starfarer.ui.oo0O.advanceImpl(Unknown Source)
3368 at com.fs.starfarer.ui.newui.L.advanceImpl(Unknown Source)
3369 at com.fs.starfarer.ui.OOOo.advance(Unknown Source)
3370 at com.fs.starfarer.ui.interfacenew.advanceImpl(Unknown Source)
3371 at com.fs.starfarer.ui.OOOo.advance(Unknown Source)
3372 at com.fs.starfarer.campaign.CampaignState.advance(Unknown Source)
3373 at com.fs.starfarer.BaseGameState.traverse(Unknown Source)
3374 at com.fs.state.AppDriver.begin(Unknown Source)
3375 at com.fs.starfarer.combat.CombatMain.main(Unknown Source)
3376 at com.fs.starfarer.StarfarerLauncher.o00000(Unknown Source)
3377 at com.fs.starfarer.StarfarerLauncher$1.run(Unknown Source)
3378 at java.base/java.lang.Thread.run(Unknown Source)
OK I think I found the problem. I renamed variants due to capitalization issues, apparently, the game remembers them. If you aren't starting a new save, go to the save game (make a backup first), and open the campaign HTML in Notepad++ or something. Control+F "eagle_ii" and "conquest_ii" and when you see a line like
<variantIdIfStock>conquest_ii_assault</variantIdIfStock><variantIdIfStock>eagle_ii_support</variantIdIfStock>(I believe it is this 2 variant, if it is something else follow this format)
change the a in assault and s in support to capital letters and it should be fixed.
Sorry for the mess-up, didn't expect game to remember this lol.