I have been having problems with some of my Photoshop compatible plugins, some work, some don't, even when they show as being available.
I wrote to the developer of the plugins that were not working "Redfield Plugins", and he has suggested that it is most likely an issue @ Affinity's end.
This is his reply "I suppose Affinity does not support multi-core operation plugins. The problem is not a problem of Redfield, it is a problem of Affinity. It is a good idea to send a message to Affinity support team."
I was a long-term user of Ps, and had no issues with a broad range of plugin/effects... now wanting to us Affinity Photo as my primary editor, would hope to know and see that all Ps designated plugins are able to operate within the affinity environment. Hopefully some one in Affinity product support can get this checked-out sooner rather than later.