Two problems have arisen with the new SDK 1.3.296:

1. The debug messages from the validation layer are now VVL-DEBUG-PRINTF instead of WARNING-DEBUG-PRINTF. This prevents the current callback logic from capturing the debug output values and the vertex output area is blank.
2. I made an incorrect assumption about the value of instanceApiVersion returned from vkEnumerateInstanceVersion(). It seems that this value does not match the SDK version on all platforms (e.g. matches on macOS, but not on Windows). Given this failed assumption, the logic I put in place to automatically use VK_API_VERSION_1_1 for SDKs > 1.3.290 does not work properly on Windows. This causes the sample to bog down and run very slowly with SDK 1.3.296.

I will submit a PR to fix this (again). I'm sorry about the mistake I made in 2 above, but I could not have anticipated item 1. It seems the interaction with the Validation Layer is sensitive to change and breakage.