A product in my cart is highlighted in red saying "quantity is below minimum order quantity", and the cart becomes empty when I switch to a different catalog. Is this normal?

Both behaviors are normal rules. Minimum order quantity: Each row in the cart displays the minimum order quantity for that product (the smallest one from the price tiers). When the quantity is below it, that row shows a red border, and the bottom displays "N items are below minimum order quantity, please adjust the quantity before submitting". The submit button will be disabled until you increase the quantity. Setting the quantity to 0 removes the item. Cart becomes empty when switching catalogs: The cart is tied to "this specific catalog". When a public page has multiple catalogs listed, each catalog has its own shopping cart. Switch back to the original catalog to see your items. The cart only exists in this browser tab—closing the tab or switching devices creates a new cart. After successfully placing an order or inquiry, the cart automatically clears.