I have a custom column that uses this formula to create a unique ID:
It works fine most of the time, then it seemingly drops the ID value. One thing to mention this ID value is the system generated value found in the ID column of any SharePoint List, not a user created column. So for example the first item has a unique identifier of ABC0001, the tenth has ABC0010 and so on. That worked fine and then i noticed that the unique number for what once was ABC0005 is now ABC0000. If i go to the calculated column and update the parameters in the formula it will update and resume showing the correct value, ABC0005 for this example.
Since ID is a system generated value and this formula is embedded in a column what could cause it not evaluate the formula to true and thus the unique ID randomly?