It can also be important to know how you are developing these pages. Are you coding the HTML from scratch, by hand or are you using a WYSIWYG page editor like DreamWeaver, BlueGriffon, etc.
You may need to tweak settings in your WYSIWYG editor, if you're using one.
Generally, for checkboxes, when I've looked at code it simply reads the text associated with the checkbox (its label). Nothing else is needed because "it's all there." Were I you, I'd take a look at the page source of the page you're having issues with and the page source of some random website that has a collection of checkboxes that work as expected and see where in the HTML they differ.
Brian - Windows 10 Home, 64-Bit, Version 1809, Build 17763
A great deal of intelligence can be invested in ignorance when the need for illusion is deep.
~ Saul Bellow, To Jerusalem and Back