Losting some feature values after checking suffix box

This is BUG or not, i am not sure. (v4.0.3)

I set a feature Weight field for product. I imported 1000 product to cart. Everything was good.

I tried to put suffix after weight feature (by writing " gr." suffix box). All weight values are lost. (field type Text for writing manually)

If i set weight of product, manually and save, i can see weight value on product detail page in features tab. But i can not recover weight feature values by re-importing my csv file.

Should i re-enter all product weight manually? :( :( :(

PS: I tried some practise on a product. After put suffix or clear suffix, same result. Values lost.