Inspiron 13 5378 not detecting headphones - Waves MaxxAudio not show in startup

Hi, my Inspiron 13 5378 (Windows 10, 1909) has stopped detecting my headphones unless they're plugged in at start up. 

I've followed the suggested fixes here https://www.dell.com/support/article/en-uk/sln310255/audio-not-automatically-switching-when-headphones-connected-to-audio-jack-on-dell-systems-with-realtek-audio?lang=en&ref=supp_lithium but to no avail.  When following Solution Two I get a popup saying Waves MaxxAudio is already installed and I need to uninstall it first however I don't see Waves MaxxAudio in Control Panel or Task Manager Start-up (only Realtek HD Audio Driver version 6.0.1.8158 A08, which SupportAssist says is the correct driver for my machine).  What I do see when searching C: for 'maxx audio installer' is 8 instances of Maxx Audio Installer (x64).msi in various folders - see screenshot.

I've also tried the Windows troubleshooter, eg, choosing the reinstall current driver option, but to no effect.

Any suggestions on how to fix this problem would be gratefully received.

Many thanks,

John