Purchased Worlds and Mash-Ups Unplayable

Hi there, for the past few months I have had a growing selection of my purchased Worlds and Mash-Up Packs from the Marketplace rendered unusable. For some reason, each pack that is unable to be used has a blue exclamation point and reads, "Downloading" even though nothing is downloading or updating... This has affected at least 50+ of my purchases and I can't use them whatsoever. 

 
I have tried uninstalling them, but then I can't redownload them. The texture packs seem to work in normal worlds, but the Mash-up worlds (ex: Toy Story Mash-up) are unable to be played-- This has been happening for the past 4 months now and the numbers of unusable worlds is growing by the week. I could really use some help here...

 
I would prefer not to completely uninstall Minecraft Windows 10 Edition in order to retrieve all the purchased worlds... I have many skin packs and worlds on this account-- 

A screenshot of the issue is attached; thanks. The Adventure Time Mash-up isn't clickable, even though it says downloading...

Thanks for viewing. - Quinn