Saw this on CurseForge, and I was having the same issue, this time with Beef Stew from Farmer's Delight, so I figured I'd make an official report.
While I'm not sure of the exact details, eating foods with high hunger/saturation values while close to full does not seem to apply the diet stats as intended. This may be a side effect of the fact that foods do not add to the diet when you are full: there may be some faulty logic in the check for that.
In any case, the issue should be reproducible with just this mod installed, according to the person who had the same issue on Curseforge. If this isn't the case, feel free to ask me for a full mod list.

Small correction: Aquaculture 2 adds fish fillets, which restore 2 hunger and 1 1/2 saturation (in shanks, not points). If this makes me full, then I still do not get the diet benefits.