> Since I have over 100 million food, it can not be due to lack of capacity / storage ...

It can. e.g. Yielding, and errands add to stock, regardless of buildings or capacity.

> Will the Ress be produced only when I am online?

No, always. Test: Be well under capacity. Note amounts. Come back 5 minutes later. They will have increased. Repeat test, but be the opposite of what you were - logged in or out. They will have increased.

> The production should actually run continuously, right?

It does.

Go Palace / Statistics / {RSS}

- better not food, at first. Food consumption rate complicates things.

Note there: Production per hour, 'You have', '{RSS} capacity'.

As long as you are under capacity, your production continues.

- if your errands or yielding puts you above capacity, production stops.

- with this you can predict how long until your production stops. When you get near it, send it to a buddy so your production continues. When you do a large build / study, have them send it back. Return the favour. You send stone, they send lumber, sort of thing.

= Yep, you lose the tax back and forth, but when builds or studies take more than your capacity, you have little choice - if you want to keep production producing.

Food is the same, but troop consumption makes the simple arithmetic of the above a titch more complicated.

Check out the fan guides in the forum. Especially anything by test, and on farming.

> Help would be grateful ...

Been here. Done this. GL&HF! :)