I believe the fix for this is going to be to convert the plain dates (with no time) to some base timezone other than UTC. The question of course is which one. GoToMyAccounts is used in a lot of countries, so we can't just assume that a fixed date (2018-06-12) should be EST or PST or something like that. We DO have a setting in the portal called home timezone in the region settings. However, I do not think it is being utilized in that way at this time.
The proper fix to all this is to use the home timezone as a time basis for fixed dates like invoice date and due date. That way, the date will always be based on the local time for the company.