Questions · Buy
Should we stop preselecting a variant?
No. The preselected default is what lets agents buy anything while the option controls do not work for them. Fix the controls and keep the default: then agents can buy the default or choose another, which is what a shopper would expect.
Why it happens
Themes commonly preselect the first available variant so that add to cart works the moment the page loads. That keeps a purchase possible even when the option controls are built in a way an agent cannot operate, such as options that only respond to a hover or controls built from elements that are not form controls.
The agent can see the other options and cannot select them, so it can only ever buy the default. Whether that is the product the shopper wanted depends on the default.
This comes up at the Buy stage. The full treatment, including how to reproduce it and what to change, is on An agent can buy only the option already selected.
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Run a free scan and find out which of these your store actually hits.