Trying to use my Amplifi 75 again after some time away.... Updated to 2.50.2 via USB connection from a laptop running Windows 10. Updated the remote app running on my Samsung Galaxy S5 to 2.50.1. Performed a factory reset by holding the tone button and pressing in the volume knob while powering it up and waiting for the A preset light to stop blinking. Re-established the Bluetooth connection. The amplifi app on my Galaxy shows the version information I've cited above and I can successfully select different tones for the amp from my phone.
But when I try to store something I've sent as a preset to the 75 by holding down the tone button nothing happens. The tone button works properly for changing between the presets, just not for storing a new one. I cannot store a new tone after modifying one of the presets using the controls on the amp itself either. Are there some magic steps needed to make these presets over-writable that I am missing? Any suggestions for debugging this?