Ditto problem I faced but got resolved yesterday.

Go to C: and see if the CONV folder still has the converted data file.  If yes, great!  The you can add the 2018 Drake converted data to 2018 Lacerte.

If you don't have the converted data file in the CONV folder, then you will need to re-convert the data.  Not a problem and not too time consuming (I converted and reinstalled the data in 2018 and began generating organizers within 90 mins).  

Call customer service at [phone number removed] , 6 am to 5 pm PST M-F, I was able to speak to an agent after a long hold -- 2 hrs 15 min -- which is very different than what we saw at Drake.  But once you are with an agent, they are far more knowledgeable than Drake (my experience thus far and hoping it will continue).

Also, for me there was no extra fee as I have all the bells & whistles in my package.  They agent will tell you if there is a cost/fee for an additional conversion (I would be surprised if they charged extra as it would NOT be a good way to welcome us newbies).

Good luck, don't sweat, just have patience when you are holding on the phone.