Unkown Source: F11 does not follow source of `rowSums()`

[LGraz]

Describe the bug
When I press F11 on a simple function (like rowSums()) the debugger does not open its source code.

To Reproduce

1. download this minimal example debug.zip
2. set breakpoint at line 2
3. press F5 > F11 > F11

Your R code

M <- matrix(1:4, 2)
rowSums(M)

c.f. debug.zip

Expected behavior
show source of rowSums() in new tab

Actual behavior

Debugger-console seems to work, but source not shown. In sidebar it says rowSums(M) Unkown Source

Desktop (please complete the following information):

• OS: Endeavour OS (a.k.a. Arch Linux) (recent update)
• R Version: 5.4.1
• vscDebugger Version: 0.5.2
• vscode-r-debugger Version: 0.5.5

Additional context

• costom R_LIBS=/home/lukas/Work/.R (should not be a problem, right?)
• followed all advice in troubleshooting
• I tried it on 2 similar machines
• LOG file in debug.zip

Any idea?

Thanks for your project and anyones help <3