Stuck maintaining “critical” legacy applications, yet being told I’m not “innovating”

I'm having a hard time explaining and re-explaining all of my sprinted time is going towards care & feeding of internal applications. I was on the original team that wrote most of these internal tools a few years ago and now the only or co-maintainer. During a recent sit down with my manager, he asked me what I was doing to "innovate", I answered by pulling our sprint board up and showing all the tasks assigned to me, all of them were top priority, and rated at large efforts. I was met with, "well what am I going to put in your list of accomplishments?"

Like the team I'm on, like the company, but incredibly frustrated that I'm not communicating that someone has to take care of this shit.