Painting blown wet dash

[Fmill]

Looking for advice as to if I’m going about this the right or wrong way.
My house is white wetdash render, the West side has big sections of blown, cracking paint.
I’ve power washed it twice and scrubbed it with a wire brush. I’m left with areas which are a mix of base render and original paint, like I’ve got a web/net of hard original paint on top of the render. The surface seems fairly stable and hard, although it may not look it from a distance. It would literally take weeks and weeks if I had to chip off every bit of old paint.
This has been a nightmare to roll, as the roller struggles to get past the first layer of original paint, so I’ve taken to ramming a brush in the gaps to try and get a seal. I’m using pliolite.

There’s a lot of real estate to cover, and i reckon it would be impossible to guarantee I’ve got every nook and cranny filled.

Before I go any further, does anyone have any guidance on if this is the right approach?
Or do I need a stabilising solution, then apply pliolite?

 

[Wayners]

Do you know why the paint has blown off?
Any damp being sealed in as it's lime render or it it stone chipping on cement?..

 

[Fmill]

Thanks for your reply. Unsure why it’s blown, it on the side that takes all the weather, although bits have blown on other areas to a lesser extent. The gutters are cast iron, and not in the best of nick- could be that I guess. The previous owner did say he had cheapo paint on it when he did it years ago.
It’s lime render.