NLog: IIS appliction running medium trust outputs ProcessName as Unknown

NLog version: 4.7.5

Platform: .Net 4.8

Current NLog config (xml or C#, if relevant)

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd"
      autoReload="true"
      throwExceptions="true"
      internalLogLevel="Warn" internalLogFile="c:\temp\nlog-internal.log" >
  
  <!-- 
    This configuration file is generated if it does not exist and will not be updated
    The documentation for the NLog configuration can be found at https://github.com/nlog/NLog/wiki/Configuration-file
  -->
  
  <!-- optional, add some variabeles
  https://github.com/nlog/NLog/wiki/Configuration-file#variables
  -->
  <variable name="loglocation" value="c:\netadmin\logs\"/>

  <!-- 
  These are the default targets defined by netadmin. Additional targets can be added:
    See https://github.com/nlog/NLog/wiki/Targets for possible targets.
    See https://github.com/nlog/NLog/wiki/Layout-Renderers for the possible layout renderers.
  -->
  <targets>
    
    <!-- Keeps a log file for each process and day-->
    <target xsi:type="File" 
            name="ProcessLog"
            fileName="${var:loglocation}${processname}.log" 
            layout="${longdate} ${uppercase:${level}} ${message} ${exception:format=tostring}"
            keepFileOpen="true"
            concurrentWrites="true"
            archiveFileName="${var:loglocation}\archive\${processname}-{#}.log"
            archiveEvery="Day"
            archiveNumbering="DateAndSequence"
            archiveDateFormat="yyyyMMddHHmmss"
            maxArchiveFiles="90"
            
            
            />
			
	 <!-- Keeps a log file for each class and day and archive for 30 days -->
    <target xsi:type="File"
              name="ClassLog"
              fileName="${var:loglocation}${logger}.log"
              layout="${longdate} - ${callsite}${newline}${level}: ${message}${newline}${exception:format=ToString}"
              keepFileOpen="true"
              concurrentWrites="true"
              archiveFileName="${var:loglocation}\archive\${logger}-{#}.log"
              archiveEvery="Day"
              archiveNumbering="Date"
              archiveDateFormat="yyyyMMddHHmmss"
              maxArchiveFiles="30"
            />
    
    <!-- Output to debugger-->
    <target xsi:type="Console"
            name="StandardConsole"
            layout="${longdate} ${processname} ${logger} ${message} ${exception:format=tostring}"
            />
    
    <!-- Output to an attached debugger -->
    <target xsi:type="Debugger"
            name="AttachedDebugger"
            layout="${logger} ${message} ${exception:format=tostring}"
            />
			
	<target xsi:type="NLogViewer"
            name="viewer"
            includeSourceInfo="true"
            layout="${longdate}|${level:uppercase=true}|${processname}|${logger}|${message}|${exception:format=tostring}"
            address="udp://127.0.0.1:9999"/>

  </targets>

  <!-- These are the rules defined by netadmin, these can be modified and additional rules can be added to customize logging-->
  <rules>
  
	<!-- Everything needed when developing to class-files -->
    <logger name="*" minlevel="Trace" writeTo="ClassLog" enabled="false" />

    <!-- All fatal, error, warnings and info are logged to the process specific log file -->
    <logger name="*" minlevel="Trace" writeTo="ProcessLog" enabled="true"/>
    
    <!-- Everything is logged to the processlog, default not enabled -->
    <logger name="*" writeTo="ProcessLog" enabled="false"/>

    <!-- Everything is logged to the console, default not enabled -->
    <logger name="*" writeTo="Console" enabled="false"/>

    <!-- Everything is logged to an attached debugger, default not enabled -->
    <logger name="*" writeTo="AttachedDebugger" enabled="false"/>
	
	<!-- This enables use of Sentinel to view logs in real-time etc -->
    <logger name="*" minlevel="Trace" writeTo="viewer" enabled="true" />
    
  </rules>
</nlog>

• What is the current result? Most logs are written to a file named after the process, but the logs from IIS process (w3wp) are sometimes written to a file named _unknown_.log sometimes, instead of w3wp.log.

• What is the expected result? All logs should be written to files named after the process.

• Did you checked the Internal log? Yes

• Please post full exception details (message, stacktrace, inner exceptions) N/A

• Are there any workarounds? yes/no No

• Is there a version in which it did work? Yes, 4.3.7 on .NET Framework 4.5. It started happening when we updated the NuGet package from that version to 4.7.5 and .NET Framework 4.8.

• Can you help us by writing an unit test? No, probably not.