Column layout resetting to default

I can't seem to get a customized column layout to stick but only on a third library.

I have calibre's most recent update for Windows. I've had the same customized layout for all 3 libraries (no change from multiple previous calibre versions).

But after this recent update, the column layout resets back to default but only for 1 of the 3 libraries. If I try to re-customize the defaulted layout, the columns reset to default in one of the other libraries & seems to always be the third one I switch to - meaning, not necessarily the same library is reset if I switch to the others in different orders.

As in:
Library A, B & C
- only A & B will show my customized column layout, C will have reset to default
- if I re-customize C, then switch to A then B
- A will still have a customized column layout but B will have defaulted back
- if I re-customize B, then switch to C then A
- C will still have a customized column layout but A will have defaulted back
- if I re-customize A, then switch to C then B
- C will still have a customized column layout but B will have defaulted back
- & so on
It is always the third library that I switch to that resets, no matter which actual library it is.

Any ideas? I don't remember having any problems with column layout before. I've always had calibre for Windows. I've got Windows 8.1 still & have had many previous versions of calibre without this happening.