SharePoint 2016 On premise check out Behavior Question

Greetings,

Issue with uploading a document into a library, which has required columns and all the required fields were filled out in the library form box. After filling out the library form and clicking on Check in I get this messaged in red font at the bottom of the library form stating this: "The file P00_VlaidationFiles/GAER SP Cleanup Project list.xlsx has been modified by i:0#.w|nam\dzgx9t on 04 Apr 2018 07:12:56 -0400." I am a wear that part of this string message is the actual file name and my work ID credentials. But I'm sure what the -0400 stands for?  Then my only option after this is to hit the cancel button within the library form. This in turn checks this document out to me even though I filled out all the required fields. When I go back in to edit this file all the required fields I chose were removed? After I fill in all the required fields again I then have to check in the document and put in my comment if need be then everyone can see the uploaded document file. I am not sure what is causing this issue to occur. Any help or suggestions would be most helpful.