Resolve refuses to adjust to stereo

I record all audio on an iphone with a stereo mic. All my past edits I have imported the video with the stereo audio without a hitch. Now all imports of MOV or audio files from my iphone recorded are showing as mono. Music MP3s are showing as stereo.

I tried to fix this by adding the stereo fixer filter. Nothing. It just says processing is disabled. No info on how to enable it. Really frustrating. Davinci is amazing and I certainly couldn't do without it, but I'm encountering more and more problems lately that never happened with any previous versions.

Is the Audio Track configured as Stereo format?

The Stereo Fixer AFX will indicate processing is bypassed on Mono Tracks either as a channel insert or Clip effect.

All of my audio tracks are stereo. In the media pool the videos are showing up as mono. If I pan the track to the far right it just lowers the sound.

After playing around with it some more I've just found a workaround...

Right click on the audio clip in the timeline and select 'clip attributes'. Change the format from mono to stereo. Then in the source channel column select 'Embedded channel 1' for channel in right (the missing channel). This doubles up the mono.

But I'm still confused why this isn't happening automatically any more. Never had this problem in the past and I always use the same audio mic, iphone and import. The clip plays both channels when I preview it from the media pool, but the moment I drop it into the timeline only one channel plays. It also lacks the bass that I hear from the clip when I play it in the quicktime player from my desktop.

The loss of bass frequencies would indicate that the stereo channels are out of phase with each other and are being summed to mono somewhere in your audio chain in Resolve. Summing an out of phase stereo pair to mono would, amongst other things, cancel the bass frequencies. If it all worked before it means something has changed, either a setting or a cable problem.
The fact that mp3s import as stereo but your phone recordings do not might mean a problem with your stereo mic.
I would be happy to test one of your clips. You could put it on Dropbox and post a link here. If the forum wont let you post the link put a space in it so it is not recognized as a link.