I have been working with several persons' databases so far, and I'd like to share some conclusions and possible solutions.
[Edit/inserted: some report importing the Janaury 2019 workbook when last week of December is missing. I am not sure, but this may cause issues, and I wouldn't risk it. Try and fix 2018 first. Under the new version importing December may or may not be an issue, but under the previous it was for Spanish, French, Finnish, Danish and Romanian. If you have this issue, scroll through this thread here and find your language solution: https://www.theocbase.net/support-forum/post/3959-can-t-import-last-week-of-december-2018.html ]
1st. If you hadn't imported a 2019 workbook before the update you probably do not have any issues with TB and may therefore not even be visiting this site, but anyway...
2nd. Those that imported the 2019 workbook, but have a backup from before that moment: put that one back in. The software update is already in place so you do not have to do that again. Open TB, import that workbook now, and you'll be good. Only downside: you probably have to reenter data you had entered after the particular backup, but that is a very small price to pay.
3rd. If you imported the 2019 workbook before the update and do not have a backup: there may not be a full solution but do this:
In TB Settings, click 'open database location'. Close TB now..
Open the database with a good editor (for suggestion see below)
Find the table 'lmm_assignment', sort by date (click date column, perhaps twice to sort from new to old) and delete all records from 2019-01-07 and later.
Find the table 'lmm_meeting', sort by date and delete all records from 2019-01-07 and later.
Find the table 'lmm_schedule', sort by date and delete all records from 2019-01-07 and later.
[Edit, do the same for the lmm_schedule_assist table]
[Edit, doing this for January may not be enough. Display issues in December and even November were reported, and you will have to go all the way back. Make sure to make a print of the schedule and the worksheets, so you can quickly reenter the now lost assignments]
Now find the 'settings' (just that, not anything else that has 'settings' in it) table:
Find every entry that starts with Talk type: (at least you will have English, additionally you have your own language if not English, and you may have additinal languages, if you have ever used workbooks in those)
NOTE! These entries are not necessarily in successive records, certainly the new one (Apply yourself to ...) is not together with the other ones.
Values should be as follows, you'll probably find they aren't. So modify where needed:
Everything that is (or was) a video (Preparing this Month's presentation, 1st call video , 1st/2nd RV video) should have 5
Initial Call should have 6
'1st Return Visit' should have 7 (so should Return visit, if that still occurs without 1st , 2nd or 3rd)
'2nd Return Visit' should have 8
'3rd Return Visit' should have 9
'Bible Study' should have 10
'Talk' should have 11
'Apply yourself to...' should have 17
[Edit Bible Reading should have 4, or as suggested by another user, simply deleted, it will turn up again when needed]
Make sure to find every item listed here and check. If you see any other talk types (Living as Christians1, Digging for Spiritual Treasures etc) delete those records. Remember to do this for all languages you have. I do not know if that is required, but I wouldn't try my luck here as I do not know if these records interact.You don't want to start all over.
Close the database and make sure to save the changes.
If you import January now, it may still not be absolutely right, but probably better. I have not yet found out which other part of the database causes this [EDIT: usually fixing the lmm_schedule_assist table solves the issues I had when I first wrote this]. Importing February now though, will probably show no issues.
Do NOT FORGET in case 2 and 3: remove the sync file from Dropbox, or rename it. Create a new syncfile by clicking the sync icon. If the sync icon stops spinning, that doesn't mean syncing is completed. Certainly for a (new) first time you have to wait it out way longer. So do not close TB, or you'll end up with an uncomplete, or even empty sync file.
For accessing the database my personal preference is http://sqlitebrowser.org/
For editing templates I now use https://code.visualstudio.com/