Hello,
when I have System-Text (produced via popover Shift-Alt-X) on a single bar rest in a part where I have “show bar rest numbers on single bars rest” shown: once (in Write Mode) I move the System-Text via the Alt-Arrow key combination, the 1 over the single bar rest disappears. This might be a bug, but for me it is a welcome feature, as in this place the bars rest number is distracting from the System-Text G.P.
Have a look at my short screen recording here please; after I have selected the G.P. text I shift it with Alt-Arrow right key, then the music reformats and the 1 disappears: Dropbox - File Deleted
I guess single bar rests with number are considered to be multibar rests - which is always split by text. More information in this post: Multi-measure rests breaking at text - #5 by dspreadbury - Dorico - Steinberg Forums