Smarcrawl SEO analysis stays at 0%

I try to run smartcrawl SEO Analysis on ufosvoorbeginners.nl, but it doesn’t run any further than 0%. It has stayed at this percentage for 1.5 hours. I have tried re-running it but get this message:

Engines cooling down. It might take a moment before we are ready for another crawl.

I did a plugin conflict test but this did not solve it. It did run, though, but not further and the 0%.