I've got a 2020 ATV TRX420FA6 that won't go into 5th gear. All other gears (including Reverse) shift with no issue and run strong. But when I try to shift into 5th, I just get a ratcheting, or grinding sound (as though it is attempting, but just can't quite grab 5th). Oil pressure at the test ports is within range. No diagnostic trouble codes are stored that I can tell. As a sid note, this trouble appeared after non-Honda oil was run in the engine for a while. Switching back to the Honda oil has not had any affect. Any suggestions are greatly appreciated!