Ever since MacOS Sierra came out, we've had quite a few complaints of users getting access denied while accessing CIFS shares on all of our 7-Mode(8.1.4P9) filers. I've seen this behavior myself where you connect to a share and many if not all of the folders will have a red bang on them. Sometimes the red bangs will just disappear, and sometimes you have to reboot/reconnect your Mac to get them to disappear.