Build firmware with master branch -> webclient ist not working (on esp32 heltechv3)

[gertsch7003]

I have build the firmware with vscode and plattform.io.
build and flash process worked fine, but the webclient on the device didn't find the files(fs partition) for the webpage. (serial debug info)
I performed the steps from the instruction page. (with the prebuild versions this feature is working)

Any ideas what could be the problem?
-> is there a special way to flash the webfiles on the board?

Thank You All
Best Gerhard