引用自 DracoDruid：

... including all Ship designs I created using it.

I think this should be a known - and already fixed - bug?

Was it a part you got from an event?

Yes it was.

Was it supposed to be usable only once?

Because I could attach a whole bunch of them in the ship design and actually build one ship with that design.
Then it all vanished. Both from the Engine Part list in the designer as well as all designs using it .

Also is this a mission?
If yes not sure designer works in them or is designed to

It was the 2nd Terran mission with the Xelosi.
And designer at least worked in so far that the designs from the 1st Terran Tutorial mission were still available in this one.

引用自 DracoDruid：

Yes it was.

Was it supposed to be usable only once?

Because I could attach a whole bunch of them in the ship design and actually build one ship with that design.
Then it all vanished. Both from the Engine Part list in the designer as well as all designs using it .

I believe so most events are on of and you did find a bug and an old one you should not be able to design a ship with it (not 100% on this) or start more than one (that is the bug)
Will resubmit it

Well, I also found a Precursor Particle Beam and could build a bunch of ships with a bunch of those designed in. No issue there.

This thread was reported
Please do not double post bugs here was the right place
Am locking the one in discussion as duplicate