I had the same issue when I purchased an id52a. I wanted the "near repeater" function for a cross country road trip. I believe it is the same for the 51 and 52 but you can search under "near repeater" for digital or analog FM. I was really disappointed that there would always be DStar repeaters but few if any FM analog showing up. That is one of the major reasons I spent the money on this particular radio!
I am using the RT Systems software to program the rig. I figured I would call their support line, which is very highly rated, to see what they could tell me. I THINK we worked it out. When you set up a database of repeaters for these radios, at least on the RT software but I assume others too, there are database tabs at the bottom for; "memories", "skip memories", "limit memories", etc. You need to go to "DR Memories" and download a repeater list of analog FM repeaters (from Repeater Book, RFinder or the like), that includes the lat/long for the repeaters. When you then upload those back to the radio, they are included in the "near repeater" search.
I hope that works for you!
73 Warren