Hi again Peakae,
The Buffer size for my Yamaha Steinberg CI2+ is the default ‘512’ setting. However, there is a NEWER driver update available (I was unaware until just now) from v.7.3 to v.8.3. But the Steinberg site (shop/products) is down at the moment (maybe ‘maintenance’ work) ?
I am hoping such an update will cure any such bugs. 
Ta,
Paul