My father reported this issue on Friday, and three of my test systems fell ill on Monday & Tuesday. I can confirm 2.33.1+18.04ubuntu2 is not working, nor is the old 2.32.5.
I was only able to solve this problem by either configuring grub to boot revision 23 of the kernel, or by subscribing to the preview channel and upgrading to kernel 188.8.131.52
Hardware seems to play a role. I was able to boot my father’s Ubuntu on my coffeelake system without problem or delay. Coffeelake, skylake and apollo lake are all immune, while braswell and haswell are affected.
I am not sure this is a fault of snapd or something peculiar to revision 24 of the kernel