When you register a business with the state (any state, as far as I know) you can register the business with a status of "active" or "inactive". I know for my state of FL when you register online, the default is "active". When registered as active, you are affirming that the business is "in fact" open for business. So if your state taxes personal income they are expecting to receive a return for that business. If they don't, they question it of course. But if you do the initial registration as "inactive" that basically reserves the business name so that no one else can use it, and also allows you to do those "start up" things that may need to be done before you can actually open for business. For example, get the federal EIN (and state ID number if required by your state) as well as open a business banking account.
So if you registered your business with a status of "active", I would normally tell you to file a tax return, even if it's all zeros. But at this point, forget it since you're talking about tax year 2018. The late penalty for filing the 1065 is $200 per month, per partner. So with a minimum of two partners your penalty is already up to $2,000 and goes to $2,400 on Sep 16th.
So for now, leave well enough alone and if questioned on it, simply reply (formally of course) that your business was not open in 2018.
