Sometimes doesn't engage PROF yes, it gives me this error sometimes when I change the original CRZ altitude. Imagine it came from Simbrief FL350, and I see OPT altitude is FL340 so I change it to FL330, on the CDU Screen I see "wrong cruise altitude", some warning like that, not sure the sentence now, I know from there that I can't engage PROF, all flight, even in flight cruise. Think could be something with the Simbrief initial import... don't know.
PS: Doens't know it it is an "error", it just doesn't engage.