I did some recording in logic pro (latest version) on my M2 Mac Mini (with the latest version of MacOS) about a week ago and everything was fine, but yesterday, although I was able to lay down midi tracks with no problems, when connecting my 4003's rick-o-sound output into both inputs of my focusrite 2i2 3rd gen and trying to record, the direct monitor signal coming out of the focusrite sounded perfect, but all I got on the recorded track was some very quiet intermittent fizzing/crackling.
To attempt resolution of this problem, I tried different USB cables, bypassing the USB hub, increasing the buffer, enabling low latency monitoring mode, checking and double checking the MacOS & Logic Pro audio settings, examining chicken entrails etc, but nothing helped so I was unable to record any audio yesterday.
Today it was the same thing, but I did a lot of googling as well. I finally got an answer that worked — Up in the macOS toolbar there is an orange mic icon.Ii'm not sure how long it has been up there but I think it is a recent addition — it might have appeared when I set up an old iPhone to use as a webcam. Clicking on this mic icon exposes a 'Mic Mode' setting with two possible values, Standard and Voice Isolation. It was set to voice isolation so I changed it to Standard. This fixed the issue and I can now record my bass track.
Before trying to record the bass yesterday I had also tried out a newly purchased secondhand Roland E-4 voice tweaker which was delivered in the morning. I was ready to send it back as I couldn't get anything useful out of it as I was getting the same intermittent noise on the track that I later got when trying to record the bass. I'll have another go at using the E-4 later, I expect this will be a lot more fun than yesterday.
I'm not sure whether anyone else will find this information useful, but I'm putting it here as it is inevitable that I'll forget all about it and I will eventually encounter the same problem again. Having it documemented here increases the chance that future me will find this post and be able use the information to solve the issue a lot quicker.