Hello and welcome to the forum.
It appears from your attached image that only a single partition (259.79 GB) on the drive was ever constructed and that, that partition does not currently have a drive letter nor an identifiable "File System" (NTFS or Fat32, ExFat, etc., ).
It shouldn't show those three sections as unallocated, should it?
Probably not, but.... without any information as to how you may have allocated the disk space historically, it would be difficult to say for sure.
It certainly looks like, multiple partitions, had at some point been created and then the volume(s) were deleted, leaving the partitions as "unallocated"
Do you have the option of connecting the same drive to another computer, just to check and see if the results are the same.
You might consider having a look at it with something like the free version of https://www.partitionwizard.com/download.html
Just to see if things look the same using a third party tool.
It's possible that some how the MBR (Master Boot Record) and or the File Allocation Table have been damaged or that the "Dock", "Connecting Cables", or the internal cross-over drive electronics have failed or are failing, that support the drive interface (SATA Internal) to USB (external) connectivity.
Worse case, I guess you could wipe it and start over. Hope you've backed up any crtical data that may have existed on it.
Good luck and keep us posted.