I am trying to build a Teams tab using an SPFx web part for a demo. 

On my inital app the Sync to teams button in the app catalog was failing with this console error being returned...

https://{TENANT}/sites/AppCatalog/\_api/web/tenantappcatalog/SyncSolutionToTeams 400

After running into this problem I started again and this time followed the below tutorial step by step but on my tenant the Sync to Teams button is disabled (This step is near in the end in the Making the web part available in Microsoft Teams section)

<https://learn.microsoft.com/en-us/sharepoint/dev/spfx/web-parts/get-started/using-web-part-as-ms-teams-tab>

I then tried to follow the alternative method of side-loading the app by creating a manifest manually using this tutorial...

<https://learn.microsoft.com/en-us/sharepoint/dev/spfx/web-parts/guidance/creating-team-manifest-manually-for-webpart>

This resuted in the installation succeeding as far as the setup tab screen (this provides a preview of your tab in a model popup before adding the tab to a channel)

The result was "Sorry, something went wrong" (This was the end result of side-loading both my customised web part another freshly yo sharepoint generated scaffold.

Really stuck on whether there's a tenant issue or maybe some node package or SPFx version issue. 

Any thoughts would be greatly appreciated.