So you're seeing this with normal shares, not just the C$ admin shares? Those (normal ones) are the kind I use all the time without issue.
Which version(s) of Windows do you have on the two affected machines? (e.g. Win10 1909, 2004, etc.)
Is there anything in common with the two machines, such as antivirus or firewall software?
What's the exact method you're using to navigate to the share? (I usually go to mine via an alias typed in, e.g. typing /d into my file display takes me to \\myserver\myshare$, prompting me for credentials if the client side has been rebooted since the last time.)