P2725DE DP-Out issues with Windows and DSC

I've purchased a few sets of the new P2725DE/P2725D monitors (the D plugged into DP-Out of the DE) for clients so far (was using the P2723D/DE and the U2721D/DE before that), and I'm consistently seeing issues, at least on Windows laptops with AMD iGPUs (haven't had the chance to test an Intel system on them yet, but so far I'm not seeing the issue with Linux).

The issue presents as no signal on the D monitor when coming back from display-off state (these systems don't sleep when plugged in), but I don't believe it occurs every time. This can only be resolved by either power-cycling the D monitor, or restarting the computer (unplug-replug or ctrl-win-shift-B make no difference). This is only occurring when DSC is in use: i.e. in 2-lane DP (USB data priority) mode with both monitors set to 100Hz - I am not seeing the issue at 60Hz or with 4-lane mode.

So far we've been okay with the workaround, but I would like to get it resolved so we can use these monitors at full spec. It certainly smells like an issue with the P2725DE's firmware, but I also wouldn't be surprised if it were a graphics driver issue or similar. Can anyone offer insight into what's wrong, and if there is a known fix?