Dissipation Field not absorbing damage

[thehairykiwi]

So I've been using a deck full of Shard of Serendipitys lately and have naturally being drawing a few Dissipation Fields.
Now it's not my favourite card, but definitely comes in usful from time to time.
The problem is only about half the time it blocks the damage. I don't mean half the turns I mean half the games I use it in.
Naturally this has distressed me  ???

Anyone know why this is happening?

I haven't been using it much lately as you can understand but I will try to in the future and grab some screenshots

[pikachufan2164]

Having a Sanctuary in play causes your own Diss Shield to stop working.

[thehairykiwi]

'I see' said the blind man

It makes perfect sense when you say it out loud.

Cheers Pikachufan