All multi-engine planes in game suffer from that.
Anyone ever figure out why that is so? Was there some real life practice to not use WEP on remaining engine with one engine out? (avoiding excessive differential etc. etc.) You'd think that with one engine out, it would be the time you really need some extra thrust out of the remaining engine.
If you have wep on at the time your engine dies, you can still engage/disengage it.
That makes me feel that its a bug and is not intended to be so.