Changing node type results in data loss

[mfrieling]

A few days ago I changed a node from shop=bakery to amenity=cafe as well as many details like name, operator etc. I was not able to delete the shop tag but just it's value. I added the amenity tag and everything looked correct. On uploading it showed me a conflict but no usable details and later on I found out on OSM that the node has been updated will all my changes, but had neither a shop tag nor an amenity tag. So somehow the new amenity tag hasn't been properly uploaded and the empty shop tag been ignored either by the app or OSM.