I have a Vortex HST 4-16 used for my 22lr trainer.
I can adjust parallax just fine @ 50yds but targets any closer are just blurry and there is no more adjustment.
I spoke with Vortex and some mounts cause issues. Try a lighter torque setting on the front ring and move the scope back and the mount forward if you can.
The only thing broke is my wallet lol. Sold the HST and bought a PST Gen2 parallax down to 20 yds. It pays or should I say it saves to look at the specs in detail before a purchase.