Maybe it’s since 4.8. I’m not sure but I didn’t encounter this in former versions.
Editing transformation by manual key-in will not work correctly. When you click the value, the value is selected and inverse color. Then typing number into it should replace the selected value and start a new number, but no, the new typed number is concatenate in the end of the original value.
I just attempted this in 4.8 but I couldn’t get your results. Where exactly are you seeing this; everywhere, in the editor while placing objects, in the blueprint editor, etc?
Have you tried this outside of your project in a new test project?