BUG_TOPIC - Waterfall & Realplume: Issue while loading craft from unmodded save - Engine Enable/Disable Action Groups get cleared.

[HB Stratos]

I'm posting this as a separate Topic as it separately applies to two different mods I tested, and I don't want to copy-paste the same issue twice when it may have the same root cause.

The Issue: When Loading a Stock Craft into a KSP Game with EITHER Waterfall or Realplume loaded, Engine Enable/Disable Action Groups get lost.

How it should be:   how it ends up with either RealPlume or Waterfall: 

Probable Cause (guess)

The issue does not appear to lie in the configs directly, doing a grep over all of the mod folders of Realplume and Waterfall with their respecive configs I could find no line that explicitly edits the Action groups or completely deletes ModuleEngines. They however all rename ModuleEngines to ModuleEnginesFX.

This leads me to suspect that in that renaming KSP does not know how to handle a craft with such a module in place as it isn't the ModuleEngines it expected, and therefore it seems to miss every setting within the ModuleEngines that was not at default, or at least action groups. (I did not have the time to test for thrust limiters too.)

I'd be curious to hear from the devs of the respective mods about what could be causing this and how it could be fixed, as I am not familiar with KSP modding in terms of C#, and only know a little bit about Module Manager patching. It would be cool to see this fixed, because this breaks functionality of vessels that are otherwise considered fully stock in their craft file and should work in an unmodded game.

Investigation: (what lead me to my above conclusion)

Spoiler

Craft used for testing: https://kerbalx.com/The_Black_Badger/CT-6M-Phoenix 

Loaded in stock KSP:

 

The original craft is from 1.9.1, but loading it in completely stock KSP 1.12.3 results in no issues, the action groups are retained.

Loaded with RealPlume-StockConfigs only (ModuleManager, SmokeScreen, RealPlume, RealPlume-StockConfigs)

The Action groups set were both removed, reset back to none. 

Loaded with only Waterfall-StockConfigs (B-9 Part Switcher, Module Manager, Waterfall Core, Waterfall Stock Configs)

Loaded with SmokeScreen only:

  No issue here, everything fine

Loaded with RealPlume, but no configs:

 No issues here either, all good.