When trying to view flac files that have ID3 tags nothing shows up in Dopus (This is probably a good thing)
What you need to do is convert them from ID3 tags to Flac format tags. This can be done with a command line tool called TAG (freeware) available here:
http://www.synthetic-soul.co.uk/tag/
Place this anywhere then add the following command to a button:
E:\Utilities\Tag\Tag.exe --remove --force FLAC {allfilepath$} <-- substitute the full path of tag.exe for your path obviously
This will convert all flacs highlighted that contain a ID3 tag to a flac tag and they then become viewable in Dopus.
Please test this on copies before trying the originals
If you're feeling brave apparently the command :
TAG.EXE --recursive --remove --force FLAC {some directory}*.flac will recursively convert all flacs in id3 format from the specified directory though ive not tested this.
Just thought id share this if like me you're wondering why some flacs never showed their tag info in Dopus.