The idea of a Forum is to look what others have asked. At this point the front page contains at least 5 posts about the March and April workbook. Please try to not unnecessarily duplicate questions.
None of these have been answered, because there is no answer. The new workbook was posted after the latest update, so you can't expect that to be fixed without an update. If the upcoming update doesn't have the fix, maybe the next one does, so keep an eye on the release notes, please.
Assuming that with an incorrectly imported workbook, no one has made assignments yet, remove the programme for those months (Settings - LMM Meeting - Schedule (middle) tab - select the week in the top box and hit the minus sign next to it. If you have made assignments, undo them first (there is always a blank line in the assignment dropdown)
For accessing the database my personal preference is http://sqlitebrowser.org/
For editing templates I like to use http://brackets.io/