The bug when published paper did not appear in Google Scholar after posting preprints at BioRxiv and ArXiv has been described in 2014: https://academia.stackexchange.com/questions/95152/do-all-preprint-servers-have-the-non-updating-issue-in-google-scholar.
The bug occurs when preprint has been in the same state for a while. Did anyone figured out any way to avoid this bug?
Did anyone experience similar issue after posting preprints ResearchSquare? The preprint status there shows how manuscript is going through the revision process. May be it will help to avoid this Google Scholar bug?