This is only because apps are bad at sync. Quality varies; occasionally there's an app that gets it right. For example, I've used Google Docs and Google Sheets for ages now and never wanted or needed to refresh — the content is always in sync.
I can see some files on the web version of google drive that I uploaded last night, but on my other machine the Backup&Sync tool doesn't even bother downloading them.
Time to move to Dropbox I think...
It costs $30, and it's a one-time payment, no subscription.
I have been fighting weak wifi+Windows10 lately.
I try to connect, and Windows will make every appearance of connecting fine, but actually assign itself a magic IP.
And the only way to get it to budge is to open a CLI and type ipconfig /renew, as there is no GUI way to force Windows to renew its IP lease. disconnecting and reconnecting, or toggling the wifi radio off and on will only refresh the magic IP: