I don't kow if this will pertain to your problem or not. I also can not record from the Mixer setting. It is due to a confirmed bug in MJ. I have a soundblaster pci128 model ct4700 and when Mixer is selected it Mutes all of the sound card imputs when you try to record. John T has writen to me and told me that the bug is now repaired and that it wil be implimented in the next build if MJ9 to be released sometime in January. If you have the same sound card as me, this is probably your problem as it appears to be much like my problem.
I suggest you try this. After doing an auto sound level test and the "no sound detected" message appears on your screen, Double click on your volume control in the System Tray and bring up your Mixer window. Bring up the recording input controls window (usually via preferences/recording radio button) and check to see if all of your mute check boxes have been checked. If they are all checked, go ahead and uncheck them, and then run the auto sound level test again. Now go back and see of all the mute boxes have become checked again. If they are all checked, then you have the same problem as I, and must wait for the bug fix to be implimented. (or go buy a sound card that does not cause this problem)
I am running MJ8 but will not upgrade to MJ9 until the product is more bugfree. I am in no hurry.
Let us know if you have the same problem. It would be nice to know that I am not in this boat alone.
Hope this helped,
Bob Galanter