Deleting Library folder and opening results in an infinite import loop

Hi,

I'm having a problem where I'm upgrading a project from 2019 to 2020. I delete the Library folder and open in 2020, and it gets caught in an asset import infinite loop:
Asset import parameters changed:
  buildTarget: platform 13, subtarget 524288, extendedPlatform 0 -> platform 13, subtarget 524294, extendedPlatform 0
Querying for cacheable assets in Cache Server:
	eb1db967bf0de274bbaf69a845c85a50:Assets/ThirdParty/Photon/PhotonUtilities/PackObject/CodeGen/Editor/Resources/TypeCatalogue.asset
RemoteAssetCache - Download - Metadata - success:true, namespace:defaultmetadata, key:da83a48a61a11ea4273cdfe433e786cf
Start importing Assets/ThirdParty/Photon/PhotonUtilities/PackObject/CodeGen/Editor/Resources/TypeCatalogue.asset using Guid(eb1db967bf0de274bbaf69a845c85a50) Importer(-1,00000000000000000000000000000000)  -> (artifact id: 'e71db3b5a0143d7fcfc9784dc73a4199') in 0.001246 seconds
RemoteAssetCache::AddArtifactToCacheServer - artifactKey='Guid(eb1db967bf0de274bbaf69a845c85a50) Importer(-1,00000000000000000000000000000000)' Artifact id='e71db3b5a0143d7fcfc9784dc73a4199' Key (and library path)='Library/Artifacts/0e/0e5020e2b37a1c489a0c08bfafe3ff7a'
RemoteAssetCache - Upload - Artifact - success:true, namespace:defaultmetadata, key:0e5020e2b37a1c489a0c08bfafe3ff7a
RemoteAssetCache - Download - Metadata - success:true, namespace:defaultmetadata, key:da83a48a61a11ea4273cdfe433e786cf
RemoteAssetCache - Upload - Metadata - success:true, namespace:defaultmetadata, key:da83a48a61a11ea4273cdfe433e786cf
Global asset import parameters have been changed during import. Importing is restarted. See editor.log for details.
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Photon.Compression.Internal.TypeCatalogue:EnsureExists () (at Assets/ThirdParty/Photon/PhotonUtilities/PackObject/CodeGen/TypeCatalogue.cs:210)
Photon.Compression.Internal.TypeCatalogue:Initialize () (at Assets/ThirdParty/Photon/PhotonUtilities/PackObject/CodeGen/TypeCatalogue.cs:56)

[Assets/ThirdParty/Photon/PhotonUtilities/PackObject/CodeGen/TypeCatalogue.cs line 210]


I saw a previous discussion that was dealing with a similar issue when the Photon directory was moved from the default location, but the fix for that issue that has been in place for a while seems to work fine.

The issue seems to be that TypeCatalogue does a Resources load (in EnsureExists) to check to see if the asset exists while the system is doing the huge AssetDatabase refresh, which fails and causes a code path where that asset is needlessly created again, which the AssetDatabase sees and thus triggers a reimport - which in turn causes EnsureExists to get called again, etc - going on forever.

It seems like this would be happening to anyone if they delete their Library folder and reimport. Am I missing something?

Thanks!