To reproduce:
Map: WW2V3b
Jap Combat move phase.
Add 3 extra Jap transports to SZ62 (so there are 4 total).
Load 1 inf from Jap to transports.
Unload 1 inf to Buryatia SSR.
Try moving a transport (fails).
Try loading a transport (also fails).
If all units are loaded before the attack move is performed there are no issues.
The post load/unload movement issue has been resolved... however, you're still unable to load subsequent units onto any of the Trns. The code in question is in MoveDelegate.mapTransportsToLoad, but I'm not going to touch it right now as I think it's likely to introduce a bug. I've made a TODO in the code to review the code and try to find a solution.
I believe I have it sorted out for the next build.
But it does present a bit of a quirk. In the example you give, if you load 7 inf to trns, then try to unload the singleton infantry, you can still load an 8th infantry into the SZ. This appears to be because the engine ignores your unload of the singleton infantry in favor of one of the paired infantry. That's an intersting quirk, but a different issue from the one here. I can look into it further.
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