Volume is marked as dirty. WTF

Hi, I have a Toshiba 2TB external hard drive that is formatted NTFS. I bought Paragon NTFS for Mac about a month ago, primarily to connect to this external drive, and a couple smaller ones that I have. It has worked fine previously, but today it tells me 'Failure when trying to mount volume'. When I click on 'verify' in the Paragon NTFS settings, it tells me 'Volume is marked as dirty.' What does this mean, and how do I correct it? I have not used this drive with any other computer since it was last mounted. I need to access pictures and information on this drive.

Thanks.

same issue. it stopped mounting hdd and now shows such message

same issue.
'Failure when trying to mount volume' and 'Volume is marked as dirty.'
Mounting external drive on Windows is ok.

How to use CHKDSK