Catch2 junit reporter suddenly writes empty file

**Describe the bug**
When running my tests with the junit reporter without "--out", I get the report in the console. When running the exact same exe with "--out test.xml", the test.xml is empty (zero byte).
Calling the exact same exe with exact same arguments from within Visual Studio produces a non-empty file !!

**Expected behavior**
The output file shouldn't be empty

**Reproduction steps**
No idea, it broke suddenly, perhaps due to compiler update ?!?

**Platform information:**

- OS: **Windows NT**
- Compiler+version: **Visual Studio 17.4.14**
- Catch version: **v2.13.10**

**Additional context**
Add any other context about the problem here.