What version are you running? Under version 13.2 your plot is continuous and looks fine.
You do notice that you have PlotStyle->{Dashing[Block],Black} Do you really want a dashed plot when you are asking why you are seeing gaps in your plot, but I don't think that is your issue?
What happens if you include PlotPoints->100 or PlotPoints->250 to increase the number of sampling points? Pushing that up too much will slow it down, but may improve the quality.
