Apparently ‘They’ are not taking subscriptions at the moment.
This topic should not be marked solved.
When I had this problem, it also only occurred on Wayland.
If his problem is caused by something other than what it was for me, then only submitting a proper bug report to KDE will be helpful, or he can continue waiting for the problem on Wayland to solve itself.
In 23 posts (albeit a merge of two threads on the same topic) there has been no definitive response by the OP to confirm a solution to the original problem of Spectacle failing to start in Wayland.
The marked solution has been removed as it served no purpose apart from highlighting that the original topic was likewise left without any clear solution.
If you are still experiencing difficulties with Spectacle, please submit a report directly to KDE as suggested (above), or if you have further information or need to add anything constructive, please ask Moderation staff (via PM) to re-open the topic.
Regards.