Make sure to add the proper amount of MEKP catalyst to the resin before hotcoating. It will not cure without it (unless it's UV cure resin)
Poly resin has a 6 month shelf life then it starts to thicken and have curing issues. This may be what you're experiencing.
Also, always shake the 250B Hotcoat resin with wax included before use to disperse the wax evenly. It is possible the wax migrated to the bottom of the jug which would make the resin remain sticky.
You can remove the sticky resin with Acetone and a rag. Scrape what you can off first then wipe the rest off...