I’m using Themify with Elementor.
Theme: OceanWP.
I’m using the Products widget of Elementor (pro) to display products (not archive products).
Make sure your define the amount of products you want to display, in my case 5 columns and 4 rows (elementor widget). Make sure to sync these settings with themify filter, that is, products per page = 20.
5 * 4 = 20, pagination as usual
I think a mismatch of total amount can cause this problem you’re describing.