What do you do when avoiding railroading just gives you stuck players?

I’m seeking some newbie GM advice. I’m an experienced rpg player, but am much less experienced as a GM

I was recently running an D&D 5e adventure, where the players would be investigating in a town that had some problems with trade caravans being attacked. They started at the local Sheriffs office who tipped them that a local relatively new thieving guild was active in the area. The thieving guild wasn’t raiding the caravans, but I thought it might add a little plot twist to get the guild involved. My thought was to have the PCs eventually figure out that the guild wasn’t behind the problem and would need to investigate the local country-side to discover the problem. I had a few encounters written out, but I wasn’t fully sure how the PCs would reach their end goal of figuring out the source of the problem. I guess I thought that over-planning would be railroading and I wanted to give the players some freedom.

The players were often confused and unsure what to do. There wasn’t quite the excitement I was hoping for. They were eventually invited to a parley with the thieves guild but were not sure what to do with the thieves, so eventually just attacked them. It was ok, but not spectacular.

What do you do when your players seem stuck?