csv file upload is not accepted where excel csv file upload is

I am trying to upload my Libre Open Office Calc csv to a public alert website that accepts excel csv files when tested. I get an error that says only csv files accepted. Does anyone know why it would not accept the Open Office version? the website folks actually want me to ask you all as they do not understand it themselves. I found something online somewhere that mentioned open office MIME is text/ plain as opposed to text/csv. Does this have anything to do with it and, if so, can it be changed anywhere? Thank you!

Your problem is most possibly related to some differences in CSV structure. CSV is very loosely defined format with many varieties; up to recently, there was even no standard for it. LibreOffice allows to output CSV with different settings; that requires editing filter settings in Save As dialog. But to know which settings to change, you need to inspect the differences between the “correct” CSVs accepted by the service, and the CSV generated by LO by default.

MIME type definitely is not related to the problem. If you provide the two kinds of CSVs in attachments here, you may get an advice.