Area effect clouds that have the "HiddenEffect" nbt tag in there Effects data don't apply the effect correctly. Instead they sometimes only apply the hidden effect or the actual effect but not both. The player should be able to receive effects from the area effect cloud that also have the "HiddenEffect" nbt tag included. If the players does not have the specific effect the area effect cloud applies. The nbt tag should just be copied over together with the "HiddenEffect" nbt tag.

I recorded a reverence video but it is larger then 10MB and therefore can't be attached to the references. I uploaded it to drop box though and attached some pictures of the video. Here is the download link for the video: https://www.dropbox.com/s/znf5krhz2vlssd9/reference_video.mkv?dl=1