I shouldn't put the blame on your mod, it could be anything. Like I said it's just the only thing that is new for me, in regards to which mods I am using.
I rebought the Lansen just to see what the selling screen looked like.
The VStab and rammer are common across both setups, only the second setup has the hardening.
But it still doesn't make any sense, I checked to make sure everything was send to depot. I don't understand why it would sell it.
Maybe it's just easier to say I'm wrong and that "Sell" was selected for the hardening, when I sold the tanks. But I can't believe I'd make that mistake twice... If there is no fault with your mod, I guess that is the only logical reason left.
Something else I noticed that is probably nothing to do with the mod, as I'm in Safe Mode:
The "Sell" remains greyed out even when the correct amount is entered.
I can sell it if I sell the hardening, for 1,440,000, but not if I select send to depot.
It's the same for other tanks. Does this happen for anyone else?