WB has never worked well with Thunderbird.  You should probably include a description of your issue and a screenshot.

Hello,

Sorry to hear you are having issues. But, as Tom said, Thunderbird never worked well with WB by default. But if you really need to. There is a work around that suggested in this thread Starting from reply#59 https://forums.stardock.com/491626/page/3/#3731175

Thank you.

Basj,

Stardock Community Assistant.

It seems that other Mozilla apps don't play well with WB, either.  Firefox doesn't skin properly and has to be excluded for it to appear correctly in default settings.  However, Thunderbird has another issue that prompted me to discontinue using it.  It was sending 2 to 3 copies of every email I sent, sometimes more.  At one point it sent 6 copies of a particular email, which prompted an me to switch to Win 10's built-in email app after I got an angered response from the recipient.

WB seems to work well with Thuncerbird version 52.9.1, so will keep that version, just thought someone might have an idea on latter versions

Have not had a problem with firefox am using version 64.0