SUMMARY It does not work if one uses special packages like nicematrix or tikz libraries like cd. STEPS TO REPRODUCE 1. Put the cursor in a math environment 2. Apply QuickPreview 3. OBSERVED RESULT No preview, replying "no math group" EXPECTED RESULT Preview SOFTWARE/OS VERSIONS Linux: Fedora 34 (available in About System) KDE Plasma Version: 5.21 KDE Frameworks Version: 5.81 Qt Version: 5.15 ADDITIONAL INFORMATION