Crates failing to move

Engine prime 1.2.2 My crates on the left hand of the screen are failing to move across to my drive crates any ideas ? I am having to manually open a crate and move over batch files. So a question has to be asked, have I reached that 2.4gb ceiling or 10K songs Denon do not recommend going above with the SC5000 if so the Prime 4 boasts the use of a 1TB drive. UPDATE 14th Feb. Windows 10, Engine Prime 1.2.2 and a Seagate 1TB SSD 2.5 Sata hard formatted to Exfat ready for Prime 4. 8000 songs added to the ssd in their various crates no problems. Full crate pick and drop now fails, so manually making crates and sub crates in ssd drive column, now batch pick and drop from Engine Libary to crate on ssd fails, will only work if I pick and drop 3 or 4 files up at a time. Ideas anyone ?