After receiving help from @rraud (on Sound Forge 16) with the 'internal' menu, and setting the single instance behaviour default to 'TRUE', the issue still remained even though the setting in the 'internal' menu still shows as 'TRUE'.
I upgraded to 17, in the hope that it would fix my issues (evidently the old adage "a fool and his money are soon parted" rings deafeningly loud).
I've tried this multiple times with both standard and elevated permissions. Cleared the settings completely. Uninstalled, cleared ALL signs of Magix on my PC's, restarted and reinstalled...no progress with the issue.
Upon doing more trials with the settings, I found that this doesn't always happen with .WAV files but it seems that the issue happens 90% of the time with .FLAC and .MP3 in particular.
When I uncheck the 'always proxy compressed formats' option, that particular issue seems to go away. Unfortunately, it then creates a new problem - when saving the file to a lossy format (eg. MP3) it introduces skips/artefacts into the audio.
It seems that I cannot have both options enabled. This is REALLY disappointing and I'm desperate for a fix/workaround.
I do edits for DJing and also use the software for sampling my own CD rips but, since SF 14 I've had nothing but issues and I really don't want to ditch SF as I love using it and have done since SF 5.
Any help would be great, please.
Thank you,
Wayne