https://forums.geocaching.com/GC/index. ... es-issues/ is a good thread on the geocaching problem (note that thread was started over 5 years ago, in 2014, and despite the title is not limited to the preloaded file). Basically, any geocaches (loaded by any method that I've tried) are only available in the unit until the GPSr is turned off. After turning it back on, the GPSr will report "No geocaches found" - all other waypoints are fine. A workaround is to always store geocaches on the SD card, then when this occurs, it's possible to force a fix by removing the SD card, start the unit, power it back off and reinsert the SD card. With access to a computer, renaming the files will also fix it (for one power cycle).
Thanks for confirming the GLONASS fix. I was headed out on a training mission last time I ran into that, and didn't know about the workaround at the time. Thankfully the GPSr started working again after 45 or so minutes and it wasn't a real search and rescue mission.