I have a workspace with two dataflows. Neither dataflow is accessible in any way. Settings are not visible at all (not greyed out, they just don't open at all). If I try to open the dataflow, it just loads, no error message. I am not the owner of the dataflows, but I am admin in the workspace. But the same problem applies to the owner of the dataflows, not able to access either of them in any way.
Seems like could not reproduce it in my side as far as my test. When I created a dataflow in Power BI Service, it works fine that can be opened and edited.
Settings are not visible at all (not greyed out, they just don't open at all).
Perhaps you can consider providing some screenshots about this issue which can be seen clearly. In addtion, how did the owner create this dataflow, connect to the specific data source or just enter data.