Resolved. Fix listed in forum:
Hi,
There are 2 different ways to solve this problem. Do only one of them.
Method 1: Navigate to VM backend >> Configuration >> Template and disable this option: Use jQuery chosen for dropdowns in FE
Method 2: Open this CSS file: ROOT/templates/YOUR_TEMPLATE/html/com_virtuemart/assets/css/flexible.css
scroll to the very bottom and include this CSS rule:
.product-field.product-field-type-C .product-field-display { overflow: visible;}