Yep. Really unfortunate little bug. I have a module up on Steam/Nexus called Escape From Smalcatraz which is just a stand-alone scenario involving some puzzle solving. One of the puzzles calls for being able to combine sinew+sinew to create bowstring. For *some* users, not all, the items do not combine, rendering the scenario unfinishable.
I've added a fix in the form of a hidden bowstring (need to perform some convoluted steps to make it appear), but whenever a person runs into this problem, they obviously mention it in the comments (as you'd expect) and the very nature of the question is itself a spoiler for the puzzle. Makes it very hard to keep the puzzle unspoiled on the Steam page.
For reference,
please see this post and the next two posts for details on changes that appear to have been added with Friday's version update.