I've already looked into that, haven't found any possibility yet.
The problem is that the cross-site result post ID is set to a fake ID = -10, because WordPress does not support getting posts and post information from across the network without swapping blog ids. Setting a fake ID will prevent it from trying to get the post again with the incorrect information.
I initially tried to solve it by somehow storing the featured image within the post object, but it's every time parsed when the posts are printed. A possible solution would require to change both the search plugin code and the theme code as well. This is not possible to solve with additional filters unfortunately.
In my honest opinion it's not worth bothering with, a final solution might take way too much time.
However if you find anything, let me know, and I will implement it to the upcoming version 🙂Best,
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