Maybe it is just me missing something (in that case sorry for the wall of text :P) but I encountered a problem with woodcutting.

I downloaded the demo today. Started with gathering some stones and crafting a stone axe. Then tried to cut down a nearby tree trunk and log by pressing u/'action button' but kept getting the message that the log/trunk was to heavy to pick up. Then I cut down a tree (by walking into it) which resulted in a trunk. Again I could not cut down the trunk into a log (same message). 

While standing on the trunk I faced another direction and suddenly could cut the trunk into a log.  Then tried to cut the log into wood chuncks but again got the message that the log is too heavy to pick up (tried 'u' and click on the log and clicking the icon and click on the log). After turnig on the spot facing in another direction I could suddenly cut the log. My character stopped cutting because he heard someone approaching. I kill the fishmen that's trying to sneak up on me and went back to chopping, but again.. The log is too heavy to pick up. This time even after rotating no luck. I experimented some more, it seems the game doesn't take any input after pressing u (i.e. can't move) then clicking the log once in a while results in the character chopping the wood but most of the time the 'Log is too heavy to pick up!' message comes up. Sadly I wasn't able to reproduce the behaviour consistently.

<edit>I jutst thought of one more thing to try. Just restarted the game and now it seems to be working :| Will update if it happens again</edit>