mas985 and Poconos, you've both helped me identify the problem.

I removed the cartridge (which was dirtier than I expected — pollen) and ran the pump without the cartridge. It ran beautifully. Tank pressure around 8-9psi, no air in pump basket, very strong return jet.

I cleaned the cartridge and put it back in. The pump primed quickly, no air in pump basket, tank pressure around 14-15psi and noticeable drop in return jet. I ran it for a few hours.

I added the vacuum (Lil Shark). Not enough pressure for it to move on its own. Barely enough to slowly vacuum manually.

I'm upset as the salesman, as I explained what I was planning and he said the pump would work fine as long as it was primed. It worked last year 10' away with 8" lift, but struggles 30' away with 10" lift. And a little dirt on the filter is enough to stop it. I'll see if they accept a trade-in for an inground pump. What pump do you recommend for this pool (24' round, approx 14,000 gallons)?

BTW, I haven't been able to find an explanation on the mechanical difference between IG and AG pumps.