New Epson 3880 PK blockage

I've only had this printer a week and have been testing lots of different papers. Yesterday I tried a few matte papers and the printer switched to the MK tank as I expected. The matte prints came out fine.

The problem occurred when I switched back to a glossy paper, and the printer changed back to the PK tank. The print came out with no black. I ran a print check and there was no PK ink coming out at all. I then called Epson and was told to run a cleaning cycle - which I did, but still no black. I was told to run another cleaning cycle and then saw a tiny bit of black on the print check. In all, it took 3 cleanings to get the PK back.

Is this normal for the 3880? Should I expect this problem to occur every time I switch out to MK and back to PK?

Also, since this is a new printer and the inks are fresh, I suspect that an air bubble occurred in the PK - as opposed to an ink blockage. If this is true, then is there some way - such as shaking or tapping the PK cartridge - to remove air? I've seen this done in a video on You Tube with a different printer cartridge.