As a workaround
    
    $Version
    
    "12.1.1 for Mac OS X x86 (64-bit) (June 19, 2020)"
    
    data = {{{1500, 4}, {1510, 4}, {1520, 4}, {1850, 6}}, {{1500, 1}, {18100, 1}}};
    
    labels = {"a", "b"};
    
    Show[
     ListPlot[#[[1]],
        PlotStyle -> ColorData[97][#[[2]]],
        PlotLabels -> #[[3]],
        Joined -> True] & /@
      Transpose[{data, Range[Length[data]], labels}],
     PlotRange -> All,
     AxesOrigin -> {0, 0}]
[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/20CdU.png