Underextrusion after 4.3.4 firmware update  

Underextrusion after 4.3.4 firmware update

Weird problem, just updated the slicer and firmware, was using the RC firmware since changing the extruder.  Was working perfectly until the new firmware update.

Setup is Prusa Mini+ Kit running octoprint with bondtech heatbreak, internal filament sensor extruder, capricorn inside the hotend, silicone sock on hotend.

Issue is that some prints under extrude, I have ruled out the slicer, and believe it is firmware.  To test I have been heating to 230 and disconnecting the hotend bowden tube and measuring extrusion.  When it is underextruding prints it will extrude 76mm exactly when asked for 100.

Hidden settings menu has the correct 415 steps and direction set as wrong.

To solve, I have reset to default, then reset it to 415, saved and then reset. Then it will extrude 100mm on the dot.  So despite the steps being correctly displaying in the settings it appears to me to be reverting back to the default steps but not direction somehow.

I have no idea what is causing this though.