Star .356 vs narrow lube groove

I plugged holes in .356 die as per Star. Left middle holes open as bullet has a very narrow lube groove. Filled up sizer and heated up. After running a few bullets, I noticed that only about 2/3 of the groove was filled. If I repeat pump the down stroke, it will fill the groove just not on the first pump. Any ideas?

I sometimes have that happen. Usually I just need to put more pressure on the plunger.
May be that the lube groove isn't exactly centered on the orfices in the die when at full stroke. Just a wild guess.
The Star can take a little time to get the depth just right.