It will be part of the next beta+stable release.
Duplicati is pretty picky about correct remote storage. From the screenshot it appears that the error is intermittent, because the next backup will not be allowed to run if there are files missing?
My guess is that this is caused by pcloud being eventually consistent, so it takes a while before the uploaded files are reported in the file list. This causes Duplicati to give error messages, because it really expects files that uploaded to stay in place.