89 325i Auto No Reverse when warm

[BetronParks]

At cold start the car will shift into reverse fine, but doesn’t shift out of first for about a minute until the transmission warms up. After this, all forward gears work fine with no slippage or anything whatsoever. However once the transmission warms up, reverse will either engage and shudder and slip under any throttle, or just not engage at all. I’ve changed the transmission fluid and filter twice with all OEM parts and Redline D4 ATF (the second time actually made this issue worse), and run both Seafoam trans tune and Lucas Transmission fix through it? Any idea what could be causing the issue? The clutch packs are obviously fine if reverse works at cold, and if all the other gears work fine, so I’m kind of stumped.192.168.0.1 routerlogin 192.168.l.l