KiCAD has lost my part symbols

[Fulko Hew]

I recently needed to revisit a design I made 4 years ago,
(back when I was still running F33/F34)
I have since also recently upgraded to F39 (that has KiCAD V7)

And the first problem I see is that on my schematic all of the parts
have no symbols on the schematic.

What happened to them, and how can I restore them?

TIA
Fulko