Sorry to be a little slow getting back to you but I had a wedding to go to 2 weeks ago & last week was I.R.S. shot. :-p
Your Stihl #1, 55L is actually a pretty good chain steel quality wise (as compared to their poor like cousins from Oregon).
But these little chains have a pretty short 'life cycle' I'm afraid under even 'normal' usage.
The fact that your chain ran 'ok' for a short amount of time screams (to me anyway) that your chain was actually 'sharpened' by one of my guys in our shop.
However, all chains have weaknesses in terms of do's & don't and getting them anywhere near dirt of any kind is a big 'no-no' for all.
IF you were near any tree roots at all, then the fine dirt around there is like 'kryptonite' to the sharp edge; I'm talking just seconds of usage time, ok?
IF you were cutting any real oak/mesquite/hardwoods, then these little chains aren't up to the task I'm afraid.
Pine trees & boards is just about it on the usage front I'm afraid. But don't get me started on the tree pine sap there, ok? :-}
So, in conclusion, I'm pretty sure that we did sharpen your chain as I said earlier but I can't know what you were cutting at the time.
Obviously, only you know for sure.
Perhaps using another sharpening service on your chain & then cutting your same items once more would more definitely 'prove' something there.
Just a thought, thanks for contacting me via my site with your question.