2020 JD 310L sight glass reads no hydraulic oil when sitting for a few days , yes it is all level with the hoe in stores position and bucket down . After running it for an hour or so the oil will show in the site glass , but once again will go away when sitting for a little while. No leaks noticed anywhere ,
Welcome to HEF Ctpc . The hydraulic pump seal may be allowing hydraulic oil to leak into the transmission , is the transmission oil overfull ? If the transmission oil level is ok, check the oil level in the rear axle.
It could just need the hyd. oil topped up. The oil will expand when heated showing in the sight glass. I'd add hyd. oil till it reads in the sight glass and see if it goes down after it's cooled off for a few hours or the next day. This is of course if other fluid levels are correct.