Disk Management Shrink Volume wrong capacity

I have 6 partitions on my hard drive. Under Disk Management, when I select a partition and then "Shrink" all but one shows the total capacity correctly, along with the amount to shrink and then the remaining that will be left. However on one partition, when selecting shrink, the total capacity is the sum of the total plus the free, and not just the total capacity. As such, I cannot shrink this volume without an error. The capacity is about 350GB with the free about 200GB. When I select shrink, the total of the volume shows 550GB instead of 350GB. The correct capacity of 350GB shows correctly on the Disk Management listing and boxes on the initial screen and also under Properties on the File Manager. It is only when selecting the shrink option that it shows 550GB.

I would install Minitool Partition Wizard Free:
Best Free Partition Manager for Windows | MiniTool Partition Free

It has a check file system function (which is basically a GUI for chkdsk), but it also is much better at resizing and moving partitions than built in Windows Disk Management.

Actually I have EaseUS Partition Manager Pro, but my problem is on my sister's PC 2 states away, who isn't very computer literate. Do you think chkdsk might fix the problem running from a cmd window?