I am using Version: 6.4.3.2 (x64) on Dell g3 laptop running Windows 10 1909. In Impress when I add text animation using the scroll in option my text scrolls in correctly but then scrolls out again and continually cycles like this.
EDIT ebot 20200427_09.00-MEZ Taken from answer, answer deleted.
I inserted a text box, added text then right click and chose Text then the text animation tab, chose scroll in leaving everything else default. I also tried the same with the Format from the top menu same result.