I was happy to hear this today as awhile back a friend was telling me how he was getting a little disgruntled at his workplace as he wanted to grow in the company but it seemed like he would always get answers such as there are no opportunities available or that they felt he was in the best position for him at the moment. His story was typical too how he did pretty much anything the company asked for and more without technically getting compensated more.
The funny thing was all I recommended he do was ask them to document their promises first before he would go out of his way to do the extra work. For example, if they say doing various work will result in a promotion in like three months then request that be on paper as opposed to just basing it on words. Sure enough, at first when he did that they stopped expecting him to work more than what he was supposed to do. As well, when it came down to it the business really did need his help to maintain the operation. Sure enough after, they gave him a written agreement that he would be guaranteed a promotion after X amount of time, which he did get.
You expect this kind of thing to only take place from like two entrepreneurs usually, but even in an employee setting you need to be firm and have some kind of verifiable guarantee that the extra work you are putting in will result in the rewards that the business claims I feel if you are serious about growing with them. Otherwise in like this case my personal hunch was they simply wanted to keep him where he was as it seems like the safest thing to do in terms of having a reliable employee for the business for that specific position. A common scenario too is that a manager needs to make themselves look good for their personal growth and promoting people like that could be a bad thing for them as that means they have to find a new reliable candidate. You need to look out for yourself too.