Comment 14 for bug 1846423

Thunderbird 68.1.2 (64-Bit)
Lightning 68.1.2

Can confirm the behavior.
My Thunderbird Calendar is connected to SoGo 4.0.2 via CalDav by using TbSync 2.5 / CalDAV & CardDAV provider for TbSync 1.4
I have done the following:
- Exported the Calendar out of Thunderbird. Lots of calendar entries includet the folowing error:
  X-LIC-ERROR;X-LIC-ERRORTYPE=PARAMETER-VALUE-PARSE-ERROR:Got a VALUE parameter with an illegal type for property: VALUE=DURATION
- Deleted all error entries in the exported .ics file with an text editor
- Deleted all entries in Thunderbird calendar and synced with SoGo (all entries disappered in Thunderbird and SoGo)
- Imported the above edited calendar .ics file in Thunderbird and synced with SoGo.
- Exported the Calendar out of Thunderbird and Sogo again. In both exported .ics files there are the following error entries existing again:
  X-LIC-ERROR;X-LIC-ERRORTYPE=PARAMETER-VALUE-PARSE-ERROR:Got a VALUE parameter with an illegal type for property: VALUE=DURATION
- Made a new test calendar entry in Thunderbird WITHOUT a reminder entry. Exported the Thunderbird and SoGo Calendar again. There
  have been no error entries in both .ics files.
- Made a new test calendar entry in Thunderbird WITH an reminder entry. Exported the Thunderbird and SoGo Calendar. The error entry
  appears in the thunderbird .ics export file but NOT in the SoGo .ics export file.

Note: The calendar entries witch include the X-LIC-ERROR entries are not synced with my Android 9 smartphone via SoGo activesync. The entries are not visible in the android calendar.

Hope this helps a bit.