Reported in https://support.mozilla.org/en-US/questions/1311240

If a contact list is the first of multiple contacts in TO, BCC, etc in a draft or template, then compose window has only the "list" when opening the draft or template.

For example, a saved template with
To: <pizza crew>, <me>
opens in compose with just
To: <pizza crew>

I created a bug 1674652
It contains a bit more info with some testing.

Current workaround would be to put the mailing list last.

To clarify, my testing was on 83 beta and the items in bug 1674652 are correct - but not limited to Bcc and templates.

I can confirm. Maybe start debugging from around https://searchfox.org/comm-central/rev/2bf26b15e9ad7fce0f1e478fa34cd55756a0f150/mailnews/mime/src/mimedrft.cpp#1251

Realistically, this is not a release blocker. marginally dataloss.

Pushed by thunderbird@calypsoblue.org:
https://hg.mozilla.org/comm-central/rev/97973d6a7073
Fix makeFromDisplayAddress to support contact list. r=mkmelin

Comment on attachment 9185645 [details]
Bug 1674650 - Fix makeFromDisplayAddress to support contact list. r=mkmelin

[Approval Request Comment]
Regression caused by (bug #): When makeFromDisplayAddress was used by CompFields2Recipients
User impact if declined: Recipients after contact list are lost when opening draft or template
Testing completed (on c-c, etc.): Yes
Risk to taking this patch (and alternatives if risky): Low

Changes in this area affect Thunderbird across the application, and can easily have unexpected outcomes, so should definitely bake on beta (maybe a full beta) before ESR.

Comment on attachment 9185645 [details]
Bug 1674650 - Fix makeFromDisplayAddress to support contact list. r=mkmelin

[Triage Comment]
We don't plan another beta for uplifts - so this will appear in beta 84.

To avoid confusion I'm minusing for esr78, but please request again in a couple weeks after beta bake is completed

Comment on attachment 9185645 [details]
Bug 1674650 - Fix makeFromDisplayAddress to support contact list. r=mkmelin

Hi Wayne, the form is showing wsmwk: approval-comm-esr78 -, I'm unable to request again.

Comment on attachment 9185645 [details]
Bug 1674650 - Fix makeFromDisplayAddress to support contact list. r=mkmelin

[Triage Comment]
Approved for esr78.6.0

Thunderbird 78.6.0:
https://hg.mozilla.org/releases/comm-esr78/rev/614c75d9daff

Verified in testing of the Thunderbird 78.6.0 release candidate on Windows 10.