The trick with a Garmin is to treat it like a small child. Only load onto it information for a ride on a ‘need to know’ basis.
Only the necessary maps for the route, as few Waypoints as possible and as few routes/Tracks as possible. Other than this, a completely clean memory.
Then it will have less opportunity to get confused.
When composing a suite of Routes or Tracks to ride an Audax or Sportive, build the Route or Track on a route planner and then get it on Mapsource or Basecamp as a .GDB or whatever Basecamp uses.
Clear the unit of all past Maps, Waypoints, Routes, Tracks and saved Data.
Load onto the unit the relevant Map tiles, Waypoints, Routes or Tracks necessary to complete the event.
Having the units memory full or unnecessary ‘Junk’ is inviting Calamity, which seemed to be Garmin’s riding partner.
Just like the feeble human brain, it is full of unnecessary ‘Junk’ ( Football, Pop music, Eastenders etc ) which leads to confusion.