I have a Azure load balanced site.

I upgraded from a 8.5.? to 8.6.3 last week. Today I have been having issues with the examine files.

I was having errors like this

Could not find file Lock obtain timed out: SimpleFSLock@D:\home\site\wwwroot\App_Data\TEMP\ExamineIndexes\Internal\write.lock

I was also have general DB locking errors, that I have assumed are related to this

I reviewed the documentation https://our.umbraco.com/documentation/Getting-Started/Setup/Server-Setup/Load-Balancing/azure-web-apps

And realised that I was missing the

<add key="Umbraco.Core.MainDom.Lock" value="SqlMainDomLock" />

I also didn't have the TempEnvDirectoryFactory. on the multi instance site, however when I tried to add it I got this error

'D:\local\Temp\ExamineIndexes\208c38d028214323109875c10448e402\f9b60bcc5780253f4fc1164d50eacfc7_twt.fnm

I changed it back to SyncTempEnvDirectoryFactory. and it was working. However about a hour later I am getting another error

Could not create an index searcher with the supplied lucene directory ---> Lucene.Net.Index.CorruptIndexException: doc counts differ for segment _6: fieldsReader shows 4 but segmentInfo shows 1

So my current settings are (same for both instances):

<add key="Umbraco.Core.MainDom.Lock" value="SqlMainDomLock" />
  <add key="Umbraco.Core.LocalTempStorage" value="EnvironmentTemp" />
  <add key="Umbraco.Examine.LuceneDirectoryFactory" value="Examine.LuceneEngine.Directories.SyncTempEnvDirectoryFactory, Examine" />
  <add key="WEBSITE_DISABLE_OVERLAPPED_RECYCLING" value="1" />