I have the same problem on firefoxbrowsers in different operating systems. Other browsers dont have this issue on the same operating systems.
In firefox I cant move the map with left-click and moving the mouse. But I can zoome in and out with scroll wheel. And the issue only exists on https://www.openstreetmap.org. (On https://www.openstreetmap.de/karte.html it works). The mouse pointer over the map changes to a hand-icon, but left-click and moving the mouse around doesnt do anything.
Is this a known problem or a problem of my firefox-profile (cant remember, that I changed anything). Or am I to stupid?
A new firefox-profile didn’t help, its the same behavior.
I also tried different pointing devices (mice, trackball, touchpad on my laptop), no solution.
Linux works (with leftclick and with rightclick). Maybe I was wrong when I told you, that it doesnt work. It was my honest belief. Sorry for that.
Windows works too, when I exit my X-Mouse-Button-Control application, which helps me to map mousebuttons and scroll events on an old beloved PS2-Trackball. So it was my fault. Sorry for that too.
The only marginal difference is, that when moving with rightclick on linux the context-menu opens at the start (rightbutton down event) and on windows the context menu opens at stop moving (rightbutton up event). What is no problem at all.