Cannot uplod the CSV file

Hello,
I cannot upload files larger than roughly 1MB, when I do this it simply do not activate the Next button despite the fact that the green line is full.
I have checked my server settings in the Security and Performance tab and it shows upload_max_filesize = 50MB and memory_limit = 256GB.

https://ww.wp.xz.cn/plugins/wp-ultimate-csv-importer/