Stuck brakes can be either hydraulic or mechanical.
The brake hose is a four ply. Its common (in ALL vehicles) for the plys to separate and the hose act like a check valve - especially if you have stretched the hose such as articulation with a lift...
Pop the bleeder while its "stuck" (if the hose is holding back pressure the bleeder will release it - you'll then know its the hose). If popping the bleeder does not release the stuck - then the sticky is mechanical - not hydraulic - and rotor, caliper and pad replacement is needed.
Or simply change the hose first and see if the problem goes away (but then rebleeding becomes a pain) - unless its already due for a brake job, then go ahead and spend on a loaded caliper set and hose.
J Wm Bishop EA, ASADE
Waiting for the JAMBOREE at Rubicon is worse than waiting for Christmas...