French flour- help please

Being locked down due to Covid-19, the only flour I found for delivery to my home was a 25 Kg bag of organic French T65. I had wanted to try it out anyway so I thought "that's ok".

After two months trial and error with my two loaves once a week, I'm finding it very difficult to handle. I make what approximates to a pain de campagne- 85% white, 15% of either wholemeal or dark rye, refreshed starter to make a leaven of 30% of final dough.

Previously, I used either Doves strong white flour or Marriage strong bread flour, both from the UK, but available here in rural Ireland. I was able to turn out a decent bread with fairly good volume and reasonable bounce in my cast-iron saucepans acting as Dutch ovens.

However with this T65 the big differences are, first, the dough stops rising in the basket well before it reaches the expected volume and second it achieves very little oven bounce.

So far it seems that lower hydration and much less kneading or S&F makes it less likely to collapse into a sludge. I'm now managing to make acceptable loaves but without the volume.

Perhaps somebody can advise how the handling of T65 differs from more usual bread flours.

Thank you.

John