The error message feels like you have some issues with coordinates, not 100% sure thought…
About drag and drop itself, Selenium (and thus, also robotframework-seleniumlibrary) does not support html5 drag and drop events (havent checked Selenium4 if thats changed) but its possible to generate those via Javascript. SeleniumTestability has html5 support build in into drag and drop keyword but does it help you in this case, hard to say …
Could you share your robot keywords what you are really doing that fails on you ?