After changing the type of a column or columns via an update set, the columns are still behaving as if they were the previous type even though the sys_dictionary record shows the new type.
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The system will block type changes to columns that contain data. Usually, the type change was allowed when the update set was captured because there was no data in the column on the development instance. However, the instance where the update set was committed did contain data in the changed column, and thus the change was blocked. If there is no data in the column and the change was still blocked, this is likely due to a known issue PRB1246074.
Once a column is in use, it is recommended to not change the type. Instead, create a new column with the desired type, and copy the data from the old column manually. This can be done via a script as well.