WD 3TB Green after using in My Cloud EX2, shows only 746GB

So basically it shows only 746GB when connected to my PC after I pulled it from My Cloud. I tried format, clean, write zeros and used Disk Management, WD utility, EaseUS Partition Master, HDDScan, tried Samsung Galaxy to format HD and I failed. But when I installed it back to My Cloud it works fine and shows 3TB. I want to use it in my PC and bought two 6TB for my cloud and got this problem. Can anyone help me? The model of Green is WDC WD30 EZRX-00D8PB0.

How did you initialize the hard drive after writing zeros to it (GPT or MBR)? Which Operating System do you use? Is the unit detected as 3TB in your system’s BIOS?

Hi, I did and GPT and MBR and it made no difference. I use windows 10 pro and home. I didn’t try bios though. After I format HHD in My cloud, pull it and connect it to PC it shows 3 partition with errors and asks to format, but failed to do so on 2 of them. Just one partition can be formatted and it’s 746GB.