Frank, pitching up or down or not at all with flaps depends on the flap arrangement as well as the planform of the model. It also depends a lot on if the flaps are full span flaperons or if they are conventional flaps with separate outboard ailerons. And to add to the mix the percentage of the chord used by the flaps will play a part. Oh, and the tail moment length. So all in all the answer is "it depends".

On two out of the three models where I've played with flaps two of them responded with a strong nose up action from deploying flaps. On the third they didn't do anything. This last one was an ARF with narrow strip ailerons that I had set up the controls to act as flaperons just to try them out. The narrow roughly 7% width resulted in no detectable pitch change and no detectable gain in lift. I guess I'm lucky that they even worked as ailerons.

The other two were/are sailplanes. In both cases the roughly 18 to 20% chord width flaperons and flaps resulted in a fairly strong nose up response to flaps going down. One used mixed in down elevator and the other I just stuff in some forward stick manually.

The fact that your pattern model responded the other way suggests to me that there was something a trifle different or extreme in how the flaps were set up.