The bearing will contact the pressure plate lightly all the time, but there should be no pressure. Your failures suggest the bearing is exerting pressure all the time.
A common issue is the release arm pivot bushes, but I think you've done them.
As said above, the bearing slides on the nose of the gearbox and this can also wear, allowing the bearing to tilt slightly, and not return freely. So check this carefully. Do not lubricate it with anything oily/greasy as it will collect clutch dust and help it to seize. If necessary, rub it with a very soft pencil, as the graphite will lubricate well and not collect dust. You might find a graphite spray as an alternative to a builder's pencil.
Clutch cable might be tight, restricting the bearing return? Check cable, and all those pivots in the linkage.
On RHD cars there have been a few reports of the brake and clutch pedal sharing the same shaft, and the pedal gets tight, so when the brake is applied, some pressure is exerted on the clutch. This also can work the other way, applying the brakes when the clutch is operated.
Last option is a misalignment of engine to gearbox. Any misalignment will cause the bearing to act eccentrically, giving it a very hard time and a very short life.
The gearbox is located onto the engine with dowels.
Check the engine backplate to ensure it is not bent or cracked.
Check the dowel locations, the dowels need to protrude enough to do their job. They can get pushed into the backplate or gearbox and no longer locate properly.
The dowels can also cut oval holes if the gearbox has been forced together carelessly at any time in the past.
Good luck.