535d gearbox/torque convertor problem

hey guys! a friend of mine has a 535d for about a year, last year he rebuilt the box with new clutch packs, and solenoids for the mechatronics, and it was driving perfect, but after driving to dubin yesteray he encountered a problem, it seem the lock up for the torque convertor is locked on constant? it drives fine, changed gear fine but when stopped and in R or D it is trying to stall, like the convertor is not disengaging, there is no fault codes showing on inpa, today we dropped mechatronics unit and changed the tcc solenoid, but it is still the same, anyone have an idea of what would cause this? im thinking torque convertor? thanks for any help guys !

Latest update is after a spin there reset adaptations and up through the gears in trip it seems to be fine?! Still worrying haha

It will come back

Whats the issue? Torque convertor?

DEAR ALAN
I do not know your system however fluid flywheels in buses had centrifugal clutches which were similar to a Honda 50 and were a set of 10 brake shoes arranged in a circle and restrained by a spring until the flywheel spun fast enough to get them to spin out and grab the surface of the fluid flywheel/ tourque converter --- usually car converters are sealed welded units and they can be repaired however you need a lathe to weld them on -- the units I worked on were bolted together and you made your own giant o ring by gluing 6 ft of o ring rubber tighter after replacing the bearings --you were all set then for 6-10 years of trouble free service .
let me know is your lock up clutch internal or external to the converter. regards bugs.
something else occurs to me --in some boxes you can take off the sump and do a resistance check on the solonoids while operating and you could have the box trying to engage a gear on top of a gear not releasing --the solonoids only allow oil to flow in a circuit and also some boxes have test nipples on the out side where you can screw a hydraulic gauge to test pressure of oil in the circuits -before you remove the sump -- you can in some circumstances take the plug off the box and manually send a 12 volt supply to each solenoid in turn and check their operation --you should hear a quiet click from each and a release click also with the sump off . regards bugs