Creating a clone of the 'Inventory Plug-in Install' policy and having the computer as the sole target, rather than the filter for any computers that do not have that plug-in, allowed it to install.
The inventory is now running.
This looks like an issue with the 'All Computers without Inventory Plug-in' filter, or rather the 'Windows Computers without Inventory Plug-in' that the former contains. The SQL code for this is:
SELECT DISTINCT vc.[Guid] FROM vRM_Computer vc
JOIN dbo.Inv_AeX_AC_Identification d
ON d._ResourceGuid = vc.Guid
AND (LOWER(d.[OS Name]) LIKE '%windows 2000%'
OR LOWER(d.[OS Name]) LIKE '%windows xp%'
OR LOWER(d.[OS Name]) LIKE '%server 2003%'
OR LOWER(d.[OS Name]) LIKE '%2008%'
OR LOWER(d.[OS Name]) LIKE '%vista%'
OR d.[OS Name] LIKE '%7%'
OR LOWER(d.[OS Name]) LIKE '%windows 8%'
OR LOWER(d.[OS Name]) LIKE '%server 2012%'
OR LOWER(d.[OS Name]) LIKE '%embedded%')
AND d.[System Type] IN ('Win32','Win64')
AND vc.Guid NOT IN (SELECT aca._ResourceGuid
FROM Inv_AeX_AC_Client_Agent aca
WHERE aca.[Agent Class Guid] = '11E36ED4-A571-4304-90AA-F0CD2366C335'
AND aca.[Product Version] LIKE '7.%')
JOIN dbo.Inv_AeX_AC_Client_Agent t1
ON t1._ResourceGuid = vc.Guid
AND t1.[Agent Class Guid] = '43043A36-0302-4375-8086-F7DD368DCADC'
AND dbo.fnVersionCompare (t1.[Product Version], (select top 1 Version from dbo.SmpVersions where PluginGuid='43043A36-0302-4375-8086-F7DD368DCADC')) >= 0
AND vc.[IsManaged] = 1
I have already manually installed the 'Inventory Agent' but adding the following line to the code above should make it install correctly.
OR d.[OS Name] LIKE '%10%'
So it should read:
SELECT DISTINCT vc.[Guid] FROM vRM_Computer vc
JOIN dbo.Inv_AeX_AC_Identification d
ON d._ResourceGuid = vc.Guid
AND (LOWER(d.[OS Name]) LIKE '%windows 2000%'
OR LOWER(d.[OS Name]) LIKE '%windows xp%'
OR LOWER(d.[OS Name]) LIKE '%server 2003%'
OR LOWER(d.[OS Name]) LIKE '%2008%'
OR LOWER(d.[OS Name]) LIKE '%vista%'
OR d.[OS Name] LIKE '%7%'
OR d.[OS Name] LIKE '%10%'
OR LOWER(d.[OS Name]) LIKE '%windows 8%'
OR LOWER(d.[OS Name]) LIKE '%server 2012%'
OR LOWER(d.[OS Name]) LIKE '%embedded%')
AND d.[System Type] IN ('Win32','Win64')
AND vc.Guid NOT IN (SELECT aca._ResourceGuid
FROM Inv_AeX_AC_Client_Agent aca
WHERE aca.[Agent Class Guid] = '11E36ED4-A571-4304-90AA-F0CD2366C335'
AND aca.[Product Version] LIKE '7.%')
JOIN dbo.Inv_AeX_AC_Client_Agent t1
ON t1._ResourceGuid = vc.Guid
AND t1.[Agent Class Guid] = '43043A36-0302-4375-8086-F7DD368DCADC'
AND dbo.fnVersionCompare (t1.[Product Version], (select top 1 Version from dbo.SmpVersions where PluginGuid='43043A36-0302-4375-8086-F7DD368DCADC')) >= 0
AND vc.[IsManaged] = 1
NOTE: Always remember to work on clones of your policies when testing, not the originals!!
I've just found that the built-in filter 'Windows Workstations' under 'Filters/Computer Filters/Windows/Workstations' has the same issue. My Windows 10 machines does not show up as a Windows machine because of this.
But at this point I am done with tinkering as I have no idea how many other places this would need to be added/changed.