When I start Firefox, sometimes it skins and sometimes it doesn't (leaving the default Windows appearance in place). Same thing with Thunderbird. If either doesn't skin then I close it and restart it and it skins. No idea why. Insights and suggestions welcome, but this is not a critical issue -- just would be nice if the next version fixed it.
Windows 10 Enterprise (19041.vb_release.191206-1406)
WindowBlinds 10.87 (062 - Windows 10 Edition) - 64 bit OS
Window titlebar blur features are enabled on this operating system
Wblind.dll 2021/03/31 12:10:05
Wblind64.dll 2021/03/31 12:10:19
Wbsrv.dll 2021/03/31 12:10:46
WB10Config.exe 2021/03/31 12:10:52
Wbload.dll 2021/03/31 12:10:30
Screen10.exe 2021/03/31 12:10:17
Edition Windows 10 Pro
Version 20H2
Installed on 3/15/2021
OS build 19042.985
Experience Windows Feature Experience Pack 120.2212.2020.0