Thanks, Henrik!
Ctrl+1 certainly works for both numerical and standard '1' keys. It might be an issue with some other software intercepting the Ctrl+1 shortcut. Or perhaps key mapping in RadiAnt was changed:
https://www.radiantviewer.com/dicom-viewer-manual/keyboard-customization.htm
And yes, there's a "bug" causing the image drift when Ctrl+2,3,4 is pressed continuously. Not very serious one, we'll fix it one day ;-)
Merry Christmas!