It seems like the day/night cycle has glitched and mobs are spawning in broad daylight. I have only seen maybe 1 in 20 burn in the sunlight. There are also huge lighting glitches I could not fix.
MC-148605
Lighting and Mob Glitches
Resolved
Duplicate
0
Carissa
(Unassigned)
Unconfirmed
(Unassigned)
Minecraft 1.14 Pre-Release 4
Retrieved
See MC-142134 how to fix this issue.