Hi, 

we are using the Build periodically trigger with the following values:

H/30 H(6-20) * * 1-5

In theory this should trigger monday to friday between 6 and 20 every half hour.

Jenkins however shows the following under the text box:

Would last have run at Monday, September 24, 2018 10:38:49 AM CEST; would next run at Tuesday, September 25, 2018 10:08:49 AM CEST.

To me it looks like the job is only executed every half hour between 10 and 11.

From the job history I can see that the job did not run last weekend, but today on monday only 2 builds were executed, at 10:08 and 10:38 like it is displayed in the configuration.

As I found no better component, I guessed it is the core component.