you won’t get support for Sonarqube 6.7.5 anymore as this version is rather old.
Instead consider upgrading to Sonarqube 7.9.1 LTS or the latest version 8.0
(see https://www.sonarqube.org/downloads/ and choose your edition)
including Scanner, Jenkins plugin … etc. and see if the problem remains.
The issue tracking has been improved since version 6.7.5
You will have to update in any case.
6.7.5 to 7.9.1 LTS is straight, but i believe for updating to 8.0 you need to
go 6.7.5 > 7.9.1 > 8.0
see https://docs.sonarqube.org/latest/setup/upgrading/
Afterwards the issues will almost certainly have the same state, then do a bulk
edit of those issues in question and set them to ‘False positive’.
If they should reappear unexpectedly, we’ll have to look further.