This was a surprise.
I have installed the system right from the start in pt-PT language.
I just added the en-US language and made it my user's language and voilá. All integer fields are now updateable.
So, this begs the questions: Is this a bug? Should this be the default behaviour? Anyone who has git access could you mention this there in order to be solved.
P.S. I still have another post where I do not really know what is happening with the Portuguese language. Maybe someone can help out with that too. See it here: Portuguese as only language installed but everything is in English in odoo 16 | Odoo
Just tried to do it from the configuration settings in the Sales App and the same thing happens. This time I already have a way of creating a new UoM but as soon as I get into the rounding precision number I get the red line and the pop up saying
Well, I need to comment on this again. It seems that this whole Invalid Field thing is associated to a bigger picture thing, i.e. everytime I try to save a field that has got an integer as its type the system gives me this error.
Places I tried already to this are:
1. This UoM dimension field.
2. Number of dependents in the employee personal information details
3. Number of decimal places in settings
4. Number of the Day in the anual inventory date field
In short, this thing seems like a system wide issue.