A change has happened on Google's maps in just the last couple of days in mid August, 2017. I actually first noticed this at Flagstack.net. Now on theirs and our maps, you cannot zoom in and out with a scroll wheel on a mouse! The map will darken, and tell you to use Ctrl + scroll to scroll the map. Well, the + and - buttons in the lower right hand corner will work too, but I personally became very used to scrolling with the wheel.
Munzee does not appear to be affected! Maybe they know what they're doing, and fixed it quickly? I cannot personally speak for Geocaching.com, as I am no longer a premium member since 2015, and never will be again, and us lowly basic members are not allowed to use Google Maps for cache maps. It's open street map, I believe.