Camera gets stuck in busy state after command

[HannesZei]

We tried to use this library on an ESP32S2 and connected it to a Flir Lepton 3.5 on the Breakout board V2.
The first initialization seems to work fine and the status register return 0x06 (which according to the datasheet indicates successful boot and normal operation). However, after we send the first command to the camera to get the serial number or to get the next frame etc. the status switches to 0x07 indicating that it is busy with the command. This means that the functions waitCommandFinish will timeout and even after that when trying to send a command the busy status is still there.

If I understood the code correctly to get the serial number of the board no SPI connection is required or could this still be related to some sort of synchronization issue with the SPI? And the I2C connection seems to work since it can read the registers successfully.
What could cause such an error?