I connected two Sparkfun IR arrays to a Raspberry Pi 3a+ using a PCA9548A multiplexer:

Sometimes the code used read the IP of the sensors correctly:

Sometimes not, with the following string:

The same thing happens when I use only a module connected directly to the Raspberry, without the multiplexer: without any variations hw or sw, sometimes the i2C address of the module is read correctly, sometimes not
How can I solve the problem?