@claude_j_greengrass, welcome to the "page 60" club 
Which Arduino board do you use ?
The Arduino Mega 2560 ? That is the only Arduino board with 10k pullup resistors for SDA and SCL to 5V. If you connect that to a cheap sensor module, then you might push 5V into the sensor chip via its SDA and SCL pins.
If you have two level shifters in the signal path of SDA and SCL, then the signal becomes so weak, that it might no longer work. Sparkfun puts a level shifter on the main board and Adafruit puts level shifters on their modules. So if you have a Sparkfun board and Adafruit modules, than you can expect problems.
The "STEMMA", "STEMMA QT", "Qwiic", "Grove" are all wrong. That is why they have to use cables with separate wires.
A good solution is to buy a 3.3V board and buy 3.3V modules (without level shifters), perhaps with 100Ω resistors near the main board in the SDA and SCL path to lower the slew rate, and show us everything before you start making it.