Nano SD - SFTP issue

[FraSti]

My proxy-sftp task is uploading lastexport.txt with following failures:

• the file is not deleted and the export folder started accumulating files (option delete is set)

• the placeholders in the filename are not replaced => day-[YYYY]_[MM]_[DD].csv the format of the export file was ok

The issue is independent from firmware, I tried 6.1, 6.3 and 6,4, followed by a factory reset after up/downdrading.

I am wondering, if a system file could be corrupted, but find no full firmware image anywhere.

Any advice

Thanks,
Frank