Error reset of selected custom field values

[gcarne]

I have a custom field for stockable variants with two options, size and colour. The selection of size and colour is for a child product, i.e. child specific. Size is the first option and colour the second (in the FE product display size appears above colour). When selecting the product for display, it defaults the first value of both options which in my case is size S/M and colour blue.

If I first change size to L/XL and colour to red it displays correctly. If I now change the size, the colour changes to the defaulted blue which it should not do. This is an error leading to confusion or even incorrect ordering because a reset of an already set value is not expected. Does anyone know how to fix this, or is it a development issue for the VM developers?

Ref: http://www.sleepinsilk.de/en/apparel/reisenachthemd-detail

VM 2.6.10
Joomla 2.5.19