Hi, I can almost reproduce this in any notebook by inserting an error within one of the cells and watch prior successful cells become unevaluated when error has been detected in the notebook. Here are the steps to reproduce:

1. create 2 or more cells with Wolfram Language expressions
2. introduce an error within the expression of the last cell
3. evaluate the entire notebook

expect - the successful cells to remain evaluated

actual - the successful cells prior to the error change from evaluated to unevaluated (i.e. grey circle)

Furthermore, when one fixes the cell in which an error has been introduced, evaluating just the fixed cell's expression will still generate an error because the dependent cells have not been evaluated. Please see the attached notebook for an example of this issue.

Attachments:

After the failure, one can still evaluate other expressions but all cells prior to the error become unevaluated. If the cells prior to the error evaluated successfully, why do the have a grey circle instead of the standard number? Anyway, this issue and several others have been reported to Wolfram support regarding Mathematica 11.3.

I do not think that the kernel crashed because I can evaluate cells after the error.