If the dumb asses would flush it and replace the torque converter it would be fixed and done.
They introduced the 8 speed with the wrong fluid. Fluid draws moisture causes issues.
They changed fluids to Mobil 1 which fixed the moisture issue.
Torque converter is glazed from moisture. Replace it and fluid and all will be solid.
Issue is GM is being a dumb ass.
Jon, what model year did this start happening?