Pirastro Evah Pirazzi

Just this week I replaced my old strings on the up right Bass with Pirastro Evah Pirazzi (Orchestral gauge).
after two days I find that the G string is less stable than the three others.
When in long Legato (8/8 in 60 quarters per minute) the string becomes "cracky" and some times losses its tune. Especially when I apply more pressure on the bow.
My experience is with Spiro core strings. This is the first time I use a synthetic core string.
Is there is any one who used Evah pirazzi strings in the past or today - and can shed some light over this issue.
thank you