How does Defender work with other AV

Another thing I ran across that would like some explanation. Tested on both Win10/11. With both Avast and Defender checking AV with powershell 

Product GUID                : {D68DDC3A-831F-4fae-9E44-DA132C1ACF46}
Name                        : Windows Defender
Real-time Protection Status : Enabled
Computername                : [ME]
Product Executable          : windowsdefender://
Reporting Exe               : %ProgramFiles%\Windows Defender\MsMpeng.exe
Definition Status           : Up to date

Product GUID                : {EB19B86E-3998-C706-90EF-92B41EB091AF}
Name                        : Avast Antivirus
Real-time Protection Status : Enabled
Computername                : [ME]
Product Executable          : C:\Program Files\Avast Software\Avast\wsc_proxy.exe
Reporting Exe               : C:\Program Files\Avast Software\Avast\wsc_proxy.exe
Definition Status           : Up to date

and if Defender is set up to scan on occasion shows up as enabled

#when running
# Get-MpComputerStatus
AMEngineVersion                  : 1.1.24090.11
AMProductVersion                 : 4.18.24090.11
AMRunningMode                    : SxS Passive Mode
AMServiceEnabled                 : True
AMServiceVersion                 : 4.18.24090.11
AntispywareEnabled               : True
AntispywareSignatureAge          : 21
AntispywareSignatureLastUpdated  : 11/6/2024 5:05:45 AM
AntispywareSignatureVersion      : 1.421.135.0
AntivirusEnabled                 : True

...... more properties follow but not relevant here

but when I try to update, get error

#Update-MpSignature
Update-MpSignature : Virus and spyware definitions update was completed with errors.
At C:\PSFiles\AV\Defender.ps1:3 char:1
+ Update-MpSignature
+ ~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (MSFT_MpSignature:ROOT\Microsoft\...SFT_MpSignature) [Update-MpSignature], CimException
    + FullyQualifiedErrorId : HRESULT 0x80070652,Update-MpSignature
 

Is this an issue with Cim vs WMI?