.gitattributes extport-ignore doesn‘t work as expected

My .gitattributes

/Tests/ export-ignore

**Expected behavior:**

`./Tests` is excluded from archive

**Actual behavior**

`./Tests` is included

**Comment**:

if I change the line to `Tests/ export-ignore` it works but excludes `src/Whatever/Tests`, too. This is not intended. I tried a non-github (self-hosted) git repo as well as a local file path. Same result for both.