RStudio IDE does not start

One of our colleagues experiences a strange problem on a shared workstation running RHEL7 with R4.
RStudio IDE does not start anymore for her, but gives no error message at all. The corresponding os process is started and stopped.
The other colleagues who use this machine don't experience any problems. It also worked for her before.

What we did:
Everything you suggested here.
The colleague can use R (both R4 and R3.6) from the commandline with no error.
We reset the internal state.
We tested starting from a directory without any .RData, .Renviron or .Rprofile file.
We checked the environment variables: no config for R except for
"RSTUDIO_WHICH_R=/opt/R/4.1.0/bin/R"
which looks innocent to me.
We upgraded to RStudio 1.4 (wanted to do that anyway).

Do you have any additional ideas of where to look for the problem or what to check?
Thanks in advance!