The root of the issue is that the profiles that come with the printer were made in a different place with different environmental conditions to where you are and it affects the way the ink behaves. The best solution to this is to make your own profiles which can be expensive even if you do it yourself because the equipment is not cheap. The way a lot people go is to try a bunch of profiles and see which ones do best. If you have tried most of the Mimaki ones from their website, try looking around at the vinyl manufacturer's website. If you are using Arlon vinyl go to their sight in the support section and look for ICC profiles for download. Theirs could work better for you. Most major manufacturers will have these on their site.
It may be the case that your head is not firing all the nozzles which will make colors look off. If your test print is printing 100% there shouldn't be an issue. Next time you are printing watch the colors and see if they seem to fade or start to become off as the printer prints. This could be a
sign of ink flow issues.