Call Show Loading Screen show passthrough for 1 frame

We are using standard UE 5.3.2 with MetaXR plugin 65, using predominantly Blueprint.

In trying to show the loading screen, we have the camera fade to black and then show the loading screen. The problem is that once "Show Load Screen" is called, a flash of the passthrough occurs for 1 frame (at the same time the splash is shown).

After much troubleshooting, we isolated the issue to the "Show Load Screen" node. If we don't use the "Add Loading Screen Splash" or "Set Loading Screen" (just have a black loading screen) and call "Show Load Screen," then it's fine. The image we use has alpha, but have also tried with images that don't use alpha.

Our app uses VR and MR modes, so we can't turn off passthrough in settings. We have tried removing the XRPassthrough Layer Component before showing the load screen, but the passthrough flash still occurs.

Has anyone else seen this issue? Any suggestions?