Issues with variant names and weights saving

[homecraftersuk]

I have consistently had an issue of my product variant titles and product weights not saving on my website.
I will create a product, with a variant title (for example 'colour') and apply a weight to the products (essential for my shipping charges) and its all good.

Then a couple of weeks/months later I go back to that product and find the variant title has reverted to default 'size' and the weight has reverted to 0.0kg

I do use an app (powered by Blendsuite) that syncs all my products from my (non-shopify) POS system to shopify; it performs a daily sync to ensure any product changes are up to date (ie. prices and stock figures) but is only supposed to be carrying over basic information like product titles, prices, quantities and SKU's - my POS system does not carry/use weights or variants.

I guess what I am asking is, is there a fault with my POS app reverting the variant titles and weights or is there a fault in Shopify not saving them?

any insight would be appreciated!