Premiere Pro 23.6 Playback worse using Open CL Acceleration with Radeon VII than Software Only

Something has happened in recent Premiere updates for one of our PCs where the playback in a sequence is markedly worse and choppy when the Project Settings are set to GPU accelerated with Open CL for our Radeon VII graphics card. I changed the settings to Software Only and the sequence played smoothly. I have re-installed Windows, reinstalled Creative Cloud and Premiere, I have installed the latest AMD drivers for gaming and then I uninstalled that and installed the PRO version of the Radeon VII drivers. I have upgraded the system to have 64GB of RAM. Nothing has fixed the laggy playback when in Open CL mode. Around 2 weeks ago, or so, everything was fine, but something has definitely changed in Premiere that has made playback choppy, laggy and generally unusable using the video card. Has anyone else noticed this?