Long delay on nightmare creatures spawning when insane

Hello, sorry if this has been posted before, I didn't see a thread about it.

Anyway, when my character drops below the sanity threshold to spawn nightmare creatures, sometimes it's taken as much as a full in-game day for them to actually show up. The overlay, sound cues and character rocking back and forth animation will trigger as they're supposed to, the crawling horror and terrorbeak just don't appear. 

It makes it more tedious to get nightmare fuel and makes the shadow creatures less of a hazard than I believe they're intended to be, so I thought it was worthy of bringing to your attention. I've seen it happen to multiple characters (Wilson, Willow, I think also Maxwell) so it's not an issue with one character's sanity modifier or anything.

Thank you for your time and for this amazing game! <3