I could reproduce this issue with English 32-bit UE v22.20.0.49 on Windows XP SP3 x86 today and I reported it by email to IDM support.

The wrong sum was in my tests never 202 on having made the selection with mouse. It was most often 1800. But it was never the correct value 3000 independent on using normal or column mode and independent on which method was used to make the selection with mouse.

The sum was always correct when making the selection with keyboard.

Interesting to watch was also what the document map and the document window displayed in various use cases and using vertical scroll bar or the document map itself to display different positions in file after having made the selection with mouse from top to bottom or from bottom to top of file in normal and column mode using Shift+Click selection method (fast) or pressing and holding primary mouse button and moving mouse pointer over status bar or toolbar to scroll and expand selection (slow).

And I get also wrong sum on making the selection with command Edit - Select Range and entering for Line the values 1 and 3000 and for Column the values 1 and 16.

But if this wrong sum behavior occurs or not depends on the commands executed before on active file. In most cases the sum is correct even when selection was made with mouse or with command Select Range.

This issue is fixed with UE v23.10.0.1 and UES v16.10.0.01.