Actually I donīt know why you are trying to give me an unasked-for lecture?
I am well aware of the fact that all kinds of .flac (uncompressed or compressed 0-8) are taggable in the same way and also that they are all in the end bit-perfect (=losless, regardless of the used compression rate). For reasons I wonīt discuss here I wish to keep an uncompressed (!) .flac... this always works flawlessly using dbpoweramp apart from the one special described case. Itīs not the end of the world, I just wanted to point that out. Thanks to the link you provided it became clear that I am not the first one to observe the described behavior.
Not much more to say in my eyes, actually...