I can't replicate as seen in this picture:
Can you please do this test:
1. Copy one of FLAC files to c:\TestFLAC
2. Use MMW My computer tree node to read file and see if Title is truncated
3. Open Properties of c:\TestFLAC folder -> Customize -> Change to Music files
4. Check is Title is truncated in both explorer and in Details Panel
If Yes, please upload that sample file to some sharing service like dropbox, one drive, google drive, ... and send me Direct DL link to PM so that I can check it for non standard fields and metadata?