I am currently importing issues from an external system via CSV from a merger of 2 companies. These issues currently don't have a SLA so when I import them I don't want them to get an SLA. I have tried, based on a custom field where I can indicate for which product the issue is, to set up the SLA in that way the issue won't get the SLA. But even when creating a new issue, the SLA still gets into the issue.
The main reason for my request is, I don't want to change all these imported issues manually when I do the final import. That will just take me too much time.
Setup that I've made now:
The custom field is a field set up as a dropdown. In the dropdown I can choose 3 product types:
1. Current product (with SLA)
2. Product that is being imported (no SLA)
3. New product to be created (will have SLA later on when it is actually there)
Setting of the custom field:
Setting of my SLA:


So when creating an issue and changing the product, it still has an SLA which, in my opinion with the settings above, should not be the case.
Any ideas on how to solve this and make sure that this will work?