Yeah, same here.
I breed em like crazy on Holodeck, so I know what needs done.
Nothing works, can't get more than the first tier of tribbles no matter what I feed them.
I have even experimented with different foods to see if the breeding program was altered, no luck.
I have been saving blue food. I'll do some experiments tonight after work and see what else I can do.
I've been saving blue foods too, but if I can't get a (Spa) tribble to make a (Thom) tribble by giving it any food then I don't want to risk the good stuff. So far, a (Spa) tribble makes a (Spa) tribble 100% of the time.