Adobe PDF ifilter 11 and SharePoint Server 2016

We're trying to follow the MS doc to enable Adobe's PDF iFilter 11 on our SharePoint Server 2016 farm.

https://docs.microsoft.com/en-us/sharepoint/troubleshoot/lists-and-libraries/ifilter-alternative-to-the-native-pdf-parser

However, the associated commands fail for us:

$ssa = Get-SPEnterpriseSearchServiceApplication -Identity "Search Service Application"
Set-SPEnterpriseSearchFileFormatState -SearchApplication $ssa -Identity PDF -Enable $true -UseIFilter $true

Even just trying to disable the built-in PDF parser results in the same error:

Set-SPEnterpriseSearchFileFormatState -SearchApplication $ssa pdf -Enable $false

The error being thrown is:

"Set-SPEnterpriseSearchFileFormatState : The processing of files of type 'pdf' is already supported by the parsing system."

If we run:

Get-SPEnterpriseSearchFileFormat -SearchApplication $ssa pdf

We get back:

Identity   : pdf
Name       : PDF
MimeType   : application/pdf
Extension  : .pdf
BuiltIn    : True
Enabled    : True
UseIFilter : False

This appears to be an issue on SharePoint Server Subscription Edition as well according to other users:

https://techcommunity.microsoft.com/t5/sharepoint-server-subscription/set-spenterprisesearchfileformatstate-disabling-built-in-ifilter/m-p/3285494