No Access when opening

I have just got the WD 5 TB My Passport for Mac Portable Hard Drive - Time Machine Ready with Password Protection, Midnight Blue. I needed a bigger drive for all my files as I have multiple drives and its not suitable for travel etc. I have used up over 1 TB with all the files I need but unless I have a finder window permanently open I can’t access anything when I open it. I have to restart my Mac or eject and restart to access any of its volume. It says the volume is there when you do the get info and it appears on my desktop but I just can not access it it comes up blank. Can you help me as I really need this drive to work flawlessly like all my other WD drives.

Does it ask for the password once or every time you access it?

No it has never asked for a password I just restart my Mac and I am straight in but if try to open later after closing finder its just an empty page no content or access request