Oh! I see, it makes sense. The perlop page says that if you use the options on the qr// and then interpolate the variable on a bigger string on the m// , the options (msi....) get set for the whole thing too.

But it makes sense as you say, that if m wasnt specified when using the qr//, the resulting compiled regex will not "accept" it later at the m//

So yes, it is my fault and trivial - even if a bit obscure, it should have dawned to me before. It is "compiled", after all :-) Thanks!