Nevermind, the issue has arisen again. I've no idea what it could be. They couldn't both be defective.
I got a Q-tip and cleaned the sensor as well as around the small rollers on the MX ergo and the issue still persists. Now its at least usable, I've plugged it into a usb extension and its sitting on my desk, but it still has small hiccups that occur every 15 seconds or so.
However if I plug it in 2 ports lower, next to my keyboard and ethernet cable the mouse is LEGITIMATELY unusable. The stuttering is unbearably bad.
Could it be a bad driver installation of whichever one controls usb devices?
Tried reinstalling the logitech mouse driver from device manager- didn't improve the problem.
EDIT: Sorry @zombienerd I just realized I never answered your questions. The ergo is more than halfway charged, the huge is brand new out of the box- so fully charged.
The issues occured in the same day. I tried the huge- found the issue I had with the ergo was there on this new mouse as well. Switched over to the mx ergo, found the issue still there. My wired razer deathadder however, works fine.