Created attachment 126825 [details]
Lowercase changed to uppercase
A field value is changed to uppercase when it refers to another field that contains lowercase value.
Hm, there was a bug like this, caused by Calc's Software Interpreter, but that should be fixed since v220.127.116.11 and v5.1.5.
Can you confirm you are indeed using v18.104.22.168, and also check what happens if you follow step 4 from ? (checkboxes to enable/disable OpenCL and Software Interpreter are next to each other)
If your version is 22.214.171.124, please create a sample spreadsheet (let's say, by clearing out all the irrelevant cells in the existing sheet), and attach it.
*** This bug has been marked as a duplicate of bug 101866 ***