@Want To Learn
1) The "no properties available" message is normal here because the script itself is not configurable. The script simply adds new filter to the list of available filters. As long as you running script - there is new filter in the list that you can use. By removing the script - the filter disappears from the list of available filters (thus the effect becomes inaccessible). Nothing to configure in the script itself, thus you see "no properties available" message.in the Tools>Scripts
. It is pretty normal for this kind of scripts.
2) About "Crop/Pad" filter. Yeah, here I mean build-in OBS filter. The idea was to check if any filter that modifies size of the source, when it placed before this filter, affects the rendering of the filter's preview. If build-in filter works OK then sure - there is something strange is going on.