Same esp8266 Project runs from one vscode/platformio and does not from other

Since several days I see a strange behaviour: I have 2 similar esp8266 projects doing some modbus communication and sending data by an mqtt client over my wifi. This worked without problems since many weeks. But now one of the projects starts after uploading and cannot get a wifi connection. The other project works for the same board as expected.

Today I tried the same on my old notebook and all works as expected!

I’m quite lost …

I also did a reinstall of vscode/platformio on my workstation. But this did not help.

Does someone have some ideas, hints for me how to find the reason.

Regards, Walter

PS: the binaries firmware.bin and firmware.elf have the same size on workstation and notebook but different content. When I’m uploading the binaries from the notebook the application works as expected!