web log user swaps to computer name

we have a Sg310 and for some strange reason in the web log the ad user (namely me !!) keeps being replaced with the computer name with a $ after it and then proceeds to block me from the site. Moment later it back to my user name again and i can access the site again.

Should there anything i could be looking for?

log reads:

2019:04:11-10:52:26 gw1 httpproxy[10131]: id="0001" severity="info" sys="SecureWeb" sub="http" name="http access" action="pass" method="CONNECT" srcip="" dstip="" user="l.wagner" group="" ad_domain="DH" statuscode="200" cached="0" profile="REF_DefaultHTTPProfile (Default Web Filter Profile)" filteraction="REF_HttCffAllow (DHH_ICT)" size="26349" request="0xd7620700" url="web.vortex.data.microsoft.com/" referer="" error="" authtime="84" dnstime="37999" aptptime="68" cattime="94" avscantime="0" fullreqtime="385937934" device="1" auth="2" ua="" exceptions="av,sandbox,ssl,fileextension,size" category="105" reputation="unverified" categoryname="Business" country="United States" application="micrsoft" app-id="1151"

2019:04:11-10:52:28 gw1 httpproxy[10131]: id="0060" severity="info" sys="SecureWeb" sub="http" name="web request blocked, forbidden category detected" action="block" method="CONNECT" srcip="" dstip="" user="LEE-W$" group="" ad_domain="DH" statuscode="403" cached="0" profile="REF_DefaultHTTPProfile (Default Web Filter Profile)" filteraction="REF_DefaultHTTPCFFAction (Default content filter action)" size="3185" request="0xd96e2e00" url="https://outlook.live.com/" referer="" error="" authtime="80" dnstime="0" aptptime="108" cattime="74" avscantime="0" fullreqtime="219188" device="1" auth="2" ua="" exceptions="" reason="category" category="156" reputation="neutral" categoryname="Web Mail"