SourceTree froze and crashed when pull the update from "pull" button on UI screen to brunch

When I did the following steps , after that, sourcetree became never able to read a specific repository even though I did following.

I did below:

1) opened sourcetree and added repository "A".

2) repo "A" was read correctly and I was able to operate at that time

3) I created a brunch

4) I noticed there were 2 pulls in the trunk

5) I selected "pull" button on the UI screen

6) for a while I was able to use source tree but it frozen suddenly

7) then it displayed "no response" then I was forced to close sourcetree.

after that, I opened sourcetree again and added same repo "A".

but sourcetree froze and gone to "no response" status.

After that whenever I tried to add repo "A" , it gone to the freeze and no responce.  

(but when I added another repo "B", sourcetree didn't freeze and I can use smoothly. it always happens on repo "A".)

To solve this issue, I tried below but it doesn't help me.

・uninstall sourcetree and re-install

・reinstall the repo"A"

Do you have another solution?