About exporting normal maps

Hi everyone,

I have unwrapped a model following the automated process.

I have checked the normal map in S3DP: it looks good and has black background between the islands.

After exporting it, I've got a different map having purple/blue color for background with artefacts.

The question is: is there any setting allowing to get black background between islands, like in S3DP, after export?

I think it would be better for visualization.

Thanks a lot!