OK, so you already found a solution before I got the time to make a PB Great. Wanted to do it now.
So I think this is bug 2 out of 3 that there are here. I will wait for a new release with that fix and make a PG with the 3rd one. And then you can review and fix it as well
The problem originates if you:
Load SVG into HTMLImageElement
you take the image from HTMLImageElement and draw it into the canvas
and then use canvas as a DynamicTexture
then the SVG is not showing up anymore.
If that makes sense. If not. after this bug 2 with bases64 is in master and released I will make a PG.