Css minify ' error

[nam-co]

Hi DevFactory, Im having this little problem, hope one of you can help me, Im working with the new bootstrap4 and other css files, some are local, most are in S3, but Im getting this (') in the middle, before html... what can this be? I know the business is busy, but maybe you're seen this problem before, thanks (Im on L5.4)

@media print {
.hidden-print {
display: none !important;
}
}
' html, body { height.......