OS: Windows 11 23h2 64bit
XnView MP versions from 1.6.3 up to 1.6.5 are affected by this.
Tested versions 1.6.3 and 1.6.5 under Windows 11, the Windows version of 1.6.4 on Linux under Wine (this is needed because the native Linux version of XnViewMP has never been able to open .CLIP/.LIP files)
Effect: .CLIP/.LIP files are no longer being recognized as image files. Old images already in the catalog appear in the browser, but opening them full screen displays nothing. Images that are not yet thumbnailed or have been modified open directly in the respective application (Clip Studio Paint)
This behavior is not observed in XnView MP 1.6.2, where these images display normally and also are indexed and thumbnailed in the catalog with no issues.
A small screenshot of the file browser of 1.6.5:
Exact same area, but this time under 1.6.2:
