import products csv not allowed

Hi,

I am trying to import products using .csv template , utf-8, separated by commas. When i try i get a message stating this file type is not allowed due to security reasons. I’ve tried several files and computers. Worked fine for 6 months until now, no message about memory. File is 416kb and contains about 24000 cells.

I do have iThemes security and Wordfence anti-malware installed but also tried with the firewall deactivated and have not been messing around to much in the settings.

Everything is up to date except wordpress v.5 as i was hoping to wait until all extensions are compatible.

Any ideas?