I see now!
The problem indeed raised when I changed the font size selecting all the text, although I didn't create the text dragging a box.

Thank you both for your helpful suggestions and time.
I wish you all a great day!
Sovos

(I'm trying to flow and unflow the text, but nothing seems to change code-wise. I'm trying to dig further into your insightful tip.)

Hey, you got this right!
Removing the tspan tag everything works fine.
How can I do that from Inkscape?

Many thanks!

I've got no idea about that. It's standard Inkscape text (I think °.°). The code produced is <text xml:space="preserve" style="font-size:40px;font-style:normal;font-weight:normal;line-height:125%;letter-spacing:0px;word-spacing:0px;fill:#808080;fill-opacity:1;stroke:none;font-family:S...

Hey, thanks for the welcome and the reply! The links you gave me are interesting (and I thank you for them!), but they are not what I'm looking for. I think that there must be some sort of bug, as I'm trying to do something really simple that's presented in many guides, but it doesn't seem to work. ...

Am I the only one having this problem? Or is it something known that I'm supposed to go around setting things directly from the code?

If I write on the "onmouseover" section of the interactivity object property, the effect is applied to the text, but if I do it doesn't work. Does anyone have any hint on the issue?

Thanks!