TCustomImage32 and derivatives throw an AV when Control's repaintMode uses rmOptimizer and an attempt is made to clear existing layers in the control.
The workaround at this time is to set the RepaintMode to rmFull before clearing layers. Issue persists in 1.9.1 as well.
Can you please upload a test demo that demonstrates the AV. Also it would be nice if you could already find out, what is causing the AV in particular.
And does it still apply to the 1.9.1 fixes release?