Check your settings. MC won't write tag information to files if you tell it not to.
- Under "Options/General/Update tags when file info changes" the option is active.
- Under "Options/Library fields/Save in file tags (when possible)" the option is active for all relevant fields.
The effect of not saving the library changes to the files occurs with standard library fields and user defined fields as well.
When tagging, the status line says...
Saving tag changes (1 remaining)
Saving tag changes (2 remaining)
Saving tag changes (3 remaining)
.
.
.
Saving tag changes (10150 remaining)
... and so on. The number only gets higher, never lower.
After quitting MC the error message box pops up.
Restarting MC and doing "Update Library (from tags) resets the altered records to the former state in the library.
"Update Tags (from library)" does work correctly, however. All Data is written without any error.
After reinstalling MC 18.0.169 the errors don't appear any more (without having changed any option settings) and vice versa.