ZM no longer creates mp4

[Anna.Nn]

with the latest updates ZM stops to create mp4 with content when recording. Files are ony a few bytes.
Codec is h264 with libx264 encoder.
In addition I receive the following error messages:

02.06.2025 13:00:43 zmc_m2 28326 ERR Failure sending null to flush codec zm_videostore.cpp 656
02.06.2025 13:00:43 zmc_m2 28293 ERR Could not send frame (error 'Resource temporarily unavailable') zm_videostore.cpp 1247

Last version without those problems was zoneminder_1.37.66~20250520.297-bookworm

BR Anna