STIHL MS 271-Z Compression Release or Hydro Locked possibly?

Could be- but could be an overheated piston swelling and nipping up as the saw cools after stopping to refuel- ie: partially seizing.
Me, I would take the muffler off and check for scoring on the piston- but it may be happening just to the clutch side of the port and not visual yet.

Possible hydro locking- if it is hard to pull after refueling, let it cool enough to remove the sparkplug and turn the saw upside down, pull the rope a few times in that position- if raw fuel runs out the spark plug hole- then over fueling it is perhaps.

Thank you, Bob. I will check those things, as soon as possible.