I don’t know if it is helpful, but on another forum thread I see that there is some discussion about which I2C bus the camera is connected to, and perhaps the camera is on a different bus than the standard camera support software would assume. I checked with and without the stereo camera hat plugged in, and as poster c2h6 mentioned in his January 16 post, the camera hat appears to be on Bus 0x0A (10). I ran i2cdetect -y 10 with and without the camera hat, and I can see the same values on Bus 10 when the hat is connected, and they disappear when the hat is disconnected:
WITH THE HAT CONNECTED:
lsmith@raspberrypi:~ $ i2cdetect -l
i2c-20 i2c Broadcom STB : I2C adapter
i2c-10 i2c i2c-22-mux (chan_id 1) I2C adapter
i2c-1 i2c bcm2835 (i2c@7e804000) I2C adapter
i2c-21 i2c Broadcom STB : I2C adapter
i2c-0 i2c i2c-22-mux (chan_id 0) I2C adapter
i2c-22 i2c bcm2835 (i2c@7e205000) I2C adapter
lsmith@raspberrypi:~ $ i2cdetect -y 10
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: – – – – – – – –
10: – – – – – – – – – – – – – – – –
20: – – – – 24 – – – – – – – – – – –
30: – – – – – – – – – – – – – – – –
40: – – – – – – – – – – – – – – – –
50: – – – – – – – – – – – – – – – –
60: – – – – 64 – – – – – – – – – – –
70: – – – – – – – –
lsmith@raspberrypi:~ $
WITH THE HAT DISCONNECTED:
lsmith@raspberrypi:~ $ i2cdetect -l
i2c-20 i2c Broadcom STB : I2C adapter
i2c-10 i2c i2c-22-mux (chan_id 1) I2C adapter
i2c-1 i2c bcm2835 (i2c@7e804000) I2C adapter
i2c-21 i2c Broadcom STB : I2C adapter
i2c-0 i2c i2c-22-mux (chan_id 0) I2C adapter
i2c-22 i2c bcm2835 (i2c@7e205000) I2C adapter
lsmith@raspberrypi:~ $ i2cdetect -y 10
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: – – – – – – – –
10: – – – – – – – – – – – – – – – –
20: – – – – – – – – – – – – – – – –
30: – – – – – – – – – – – – – – – –
40: – – – – – – – – – – – – – – – –
50: – – – – – – – – – – – – – – – –
60: – – – – – – – – – – – – – – – –
70: – – – – – – – –