Thanks for the report, and the very helpful images here!
There was a problem with this reported in the previous build, with parts only being partially disabled in this process, and I found an issue in the code and fixed it for Alpha 4, but apparently that wasn't enough to cover all situations. I'll get this sorted for next time!
For now, consider it a lucky bonus
Well, maybe anyway. Are you sure it's still giving you power?* From the time the message says disabled through to when you detach and reattach it, there is no difference in power output on your HUD, in which case it seems to be working properly internally, as I expect it should be given the previous fix, it's just not updating your PARTS view to reflect the fact that it's disabled. (*You don't have to actually answer this or explore it further--I'll get to the bottom of this--just pointing out that this appears to be the most likely case.)
