According to your documentation at http://getbootstrap.com/docs/4.0/content/tables/, table-active class can be applied to either tr's, td's or th's. But the resulting background color will be different, with a darker color for tr's.
This could be seen in the following plunker:
http://plnkr.co/edit/aYMqCL0dKLPq9vPdDpWH?p=preview

The reason is that table-active is defined with an opacity and is applied to both the trand its td's / th's.

To fix that, instead of this selector:

.table-active, .table-active>td, .table-active>th

I would simply use:

.table-active

Another solution would be to use #ECECEC instead of rgba(0,0,0,.075).