Adding Categories To Products / White Screen Only With Categories Text

OK, so I’m not sure the best way to word this category. :)

Brand new here too.

Just installed CS-Cart 4.2.4 dd3bdcca184e3f39855a0b1d2013fb25dd6dd2c8, for a client of mine, using the CS-Cart addon feature in the dashboard of their Siteground account. The site looks OK from the front end:

When I try to add a product and assign a category, the category list looks like the attachment?

What is wrong? Any suggestions?