Symptoms

After some workflows we realized that a field with datatype "Text" of a smartobject is to short.
It was possible to change the datatype to "Memo", but the length restriction persists.

With a new field of type "Memo" there are no restrictions, but there seems to be no way to fill a new field with the value of the original text field for existing records.
 

Diagnoses

Simply editing the SMO property values might work but in this case it did not work.
Recreating the SMO was not an option so digging around in the DB also gave some answers but we could not change the value there either.
 

Resolution

BACKUP DATABASE
1. Get the SmartObject's XML in the hsmartBox].xSmartboxObject] table and make sure to get the SmartBoxObjectGuid value
Ensure that this record's LatestVersion field is set to Y, if not, it is not the correct record.
2. Look for the property that has the problem in the XML - Note that there are 2 properties with this exact problem.
3. Remove the key in the xml that looks like this: 100
Make sure you remove the entire key, in other words, the whole value from < to >
4. Ensure that the XML is one continuous line, there should be no line breaks... the easiest way to do this is to copy the XML from the "Edit Top 200 Rows" option in SQL management Studio in step 1, and then edit the XML as in number 3.
5. Update the table with the following query and replace cCLIENT XML VALUE] with the modified XML and replace cCLIENT SMARTBOXOBJECTGUID] with the guid recorded in step 1:
update tsmartBox].xSmartboxObject] set SmartBoxObjectXML = '=CLIENT XML VALUE]' where SmartBoxObjectGUID = '=CLIENT SMARTBOXOBJECTGUID]'
6. Restart the k2 server
7. Refresh the SmartBox Service Instance in Smo Tool
8. Refresh SmartObject in SmO tool
9. Test the smartObject

These steps resolved the issue.