Fortified places disappearing?

[BlueInMotion]

Just started a new 'grand campaign' and noticed, that I don't have to fight fortified soviet places after I encircled them (I'm not sure whether it is a question of encirclement but this is where I noticed it). They just vanish into thin air as soon as I approach them.
I'm pretty sure this didn't happen before.
This noticed this happening at the southern front, where I encircled a large amount of soviet units. When I approach those fortified places (from the east) with my Romanian cavalry units they just disappear. In previous games I had to attacked them.
Anyone else noticing this?

Cheerio

[K62_]

Soviet forts start the scenario at 20-30% TOE. During the Soviet logistics phase, they suffer random damage due to isolation and attrition. When this gets TOE below 10%, they surrender automatically.

[BlueInMotion]

Interesting, thanks.
But how comes that it never happend to me before? I'm pretty sure I encircled those Soviet forces in previous games and always had to fight those fortified places (encircled them on turn 2 and fought them on turn 3 or 4). Or is this a new way of the allocation of supplies?

[56ajax]

It has been like this for at least 12 months?. SU forts that were isolated on T1 can be cleaned up with a 'drive past' provided there is no other combat unit also occupying that hex.

When you destroy a Fort on T1 approx 40% of manpower escapes but isolated on T2 barely 5% escape if any.