I cycled it a bit carefully since I found some of the parts wanted to fall off if the trigger housing (lower receiver for the AR crowd

After securing the recoil spring back in the tube with little pin and then installing the buttstock, I pulled the bolt back...
...and it is stuck there. I thought it was bolt hold open, so I pressed to no avail. Then I pressed the magazine follower and nothing. Short of tapping the charging handle, what else can I try? Right now I already removed the recoil spring and the buttstock in preparation for removing the trigger housing.