Commit and Push successful and then shortly after it says I am 61 behind

[Mych]

Hi,

I've been using Sourcetree quite happily for a while now. No issues. Suddenly I have a project that I had a feature branch. Committed ok. Finished feature, merge to develop branch ok. Push to origin Ok. Within a few mins I get a badge with up arrow showing 61. I did another push to origin and all OK. Again within a few mins (no changes to the project) and it shows the badge with 61. I do another push to origin and check show output. This shows (as far as I can tell) that both sides are identical... Everything is up to date. 

git -c diff.mnemonicprefix=false -c core.quotepath=false --no-optional-locks push -v origin develop:develop
Pushing to https://xxxxxx@bitbucket.org/yyyyyy/zzzzzz.git
To https://bitbucket.org/yyyyyy/zzzzzz.git
= [up to date] develop -> develop
updating local tracking ref 'refs/remotes/origin/develop'
Everything up-to-date

Completed successfully.

And yet again after a few moment I get the badge again. What is happening? I'm using version 3.2.6 on Windows 10.

[Mych]

It seems that the remote repository had two branches (Develop and develop). Develop was the original created back in 2018, while develop was created when git-flow was introduced (or at least when I started using it). It seems both were being tracked to the local develop branch and hence the Develop was way behind. I have deleted the Develop branch via the BitBucket web site and hoped that would solve the issue but it has not. Sourcetree still thinks there is a Develop branch on the remote. See attached screenshot. 

What do I need to do?