VoiceOver: Panning thru text with a Braille Display

Braille on Apple Products

I am currently using OS 11.4 on an Image of late 2017: I have assigned two keys of my Braille display to pan left and pan right. Ina plain text document such as text edit or Word for Mac this is working perfectly, however it does'knt work in mail or Safari. Panning thru a received e-mail message e.G. would display 1 line and then, when panning on, either goes back to the beginning of the current line or even to the beginning of the e-mail message. Reading text in Safari shows similar behavior. I have been using these Braille Displays: Humanware Brilliant B80, APH Mantis, Baum Vario340, Esys 40.
The only workaround I could do so far is to downarrow at the end of a line, but I guess this is not where it's at. I wonder if anyone else has had similar experiences.

Greetings from the Black Forest in Germany