That is a finnicky angle to cut Barb. Probably as prone to some drift/movement as you push through the blade as any cut. Using sandpaper on the fence, or even a clamp to hold the stock as you crosscut. That makes sure it doesn't drift.
Blade is best for a higher count (at least 60 tooth) crosscut blade. I try to use brand new ones when doing these. Sharp carbide is good, dull, not so much, and also pitch can create drag, so old blades can sometimes spoil the work.
Those are my 2 go to tips when cutting these.
For a fix, I'm with Larry, a thin shim, and carefully sand it down, and it will all but disappear.
Bases I also agree with Larry, let the flag do the talking.