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
The wagon should, of course, be as light as possible, but strength should not be sacrificed to lightness, for on any but the regularly traveled roads, the wagon will get many a hard knock...