Is the expert level of GnuBG even useful? Or is just that it sucks at simple end game problems?

I and my opponent both had two checkers left - I had one on the 5 and one on the 2 point, my opponent's both were on the 1 point. It's my turn, center cube. So it's hit or miss. I calculate I am a 19:17 favorite and doubled. After the game, GnuBG told me that was a mistake, despite agreeing that I was a favorite in that spot. But it somehow came to the conclusion that after me doubling and my opponent taking it, my opponent would become the favorite. I was confused, as that didn't make any sense to me. It was early in a 21 points match, and the score was close, so I didn't think that would have any impact - but I let GnuBG analyze it as a money game regardless. It told me No double, beaver would be the right move. Didn't make sense to me, and I don't see how beavering would change that simple of a problem, where beavering HAD to be bad imo. Still, deactivated beavers, GnuBG tells me it's no double, take, despite me being a favorite. I recalculated, and messaged two people about it, because it didn't make any sense to me. Finally I had the expert idea to change GnuBGs analysis level from the default expert to grandmaster. And there it was, the Double, take, that I had envisioned.

So why would expert level fail to get such a super simple problem right? I mean I have no doubt GnuBG is worlds better than I am even at the expert setting. But at what point does it become unreliable? Does it have a general weakness regarding endgame patterns?