Like the title says, I open a document and my tablet (wacom bamboo pen ctl-470) works on the interface but not on the canvas. I try drawing but nothing appears until I click outside the canvas window. This started to happen from Krita 3.0 onwards. I use Windows 10 64 bit with intel graphics on an asus laptop with 8gb ram. I've used both the installed version and the portable version and I've used them both in compatibility mode for previous versions of Windows but the bug persists. I tried the recent 3.0.1 alpha build but the effect was the same. I really hope you'll look into this at your earliest convenience.

We cannot look into this. Krita works fine with Wacom tablets on Windows 10, until some Windows update kills the driver. It might even be that using Krita in a compatiblity mode is a problem with some driver versions. But in the end, it's an installation problem specific to your setup, not a problem in Krita.