Kibana version: 7.12.1 to 7.13.0

Elasticsearch version: 7.12.1 to 7.13.0

Server OS version: Debian 10 or Elastic cloud on AWS

Browser version: latest Chrome or Safari

Browser OS version: latest Chrome or Safari

Original install method (e.g. download page, yum, from source, etc.):

Debian for our own Install. No idea how you install Elastic Cloud, I guess Kubernetes

Describe the bug:

When Upgrading from 7.12.1 to 7.13.0 in some of our TSVB views the time field was gone.
Results in No Results in the dashboarda

Steps to reproduce:

1. Have a bunch of TSVB views with Time field in Kibana
2. Upgrade to 7.13.0
3. Observe No Results
4. Check views and notice that Time field is gone

Expected behavior:

Time field is converted.

Screenshots (if relevant):

Sorry company sensitive.

Errors in browser console (if relevant):

Provide logs and/or server output (if relevant):

Any additional context: