I have explorer replacement activated in prefs (all folders) and it works like a charm, unfortunately not when mounting a Macrium image file - extension mrimg. It automatically opens windows explorer. Any idea what the reason can be? Suspect an anomaly in Macrium...
Macrium may be running Explorer.exe directly, or may be using ShellExecute(Ex) on the folder and explicitly specifying the "open" verb (which goes to Explorer) rather than allowing the null/default verb to be used (which will go to Opus if Explorer Replacement is turned on).