Ardour fails to load lv2

Hi boys and Girls.

So, I’m using Ardour 6.9.0~ds0
“After Bach”
(rev 6.9.0~ds0-1build1)
Intel 64-bit

Running on Linux Mint 21.3 Virginia, on a Lenovo Thinkpad x230 i5.

I recently purchased Pianoteq 8.2.2 STAGE which works perfectly as standalone app.

However, having installed the x86-64bit lv2 in my local .lv2 folder, it seems Ardour doesn’t want to load it :
2024-06-05T20:02:12 [ERROR]: LV2: Failed to instantiate plugin https://www.modartt.com/lv2/Pianoteq8STAGE
2024-06-05T20:02:12 [WARNING]: Failed to add Synth Plugin to newly created track.

any clues?

I was previously using Pianoteq 4, that works OK but only an x386 was supplied back then.

Regards
Steve