If you are having an issue with single marker clustering, then @tscroggins shows the solution for that, however, both your original clusterGroupColors setting and this post should work This example shows random dynamic changes to foreground and background colours. <row>
<panel>
<viz type="leaflet_maps_app.maps-plus">
<search>
<query>| makeresults format=csv data="latitude,longitude
-33.7688,150.9063
-32.2773,115.7316
-27.4698,153.0251
-34.727,138.6689
-19.259,146.8169
-33.8688,151.2093
-37.9145,145.1195
-31.7467,115.7677
-33.7688,150.9063"
| eval bgp_state=mvindex(split("Down,Up",","), random() % 2)
| eval state=lower(bgp_state)
| eval clusterGroup=case(state="down","red",state="up","green",bgp_state="null","green")
| streamstats c
| eval setBg=if(state="up", "green,blue", "red,orange")
| eval setFg=if(state="up", "white,yellow", "black,grey")
| eval clusterBgColor=mvindex(split(setBg, ","), random() % 2)
| eval clusterFgColor=mvindex(split(setFg, ","), random() % 2)
| eval description=printf("<b>Item %d - %s</b>", c, bgp_state), tooltip=description</query>
<earliest>-15m</earliest>
<latest>now</latest>
<sampleRatio>1</sampleRatio>
</search>
<option name="drilldown">none</option>
<option name="leaflet_maps_app.maps-plus.cluster">1</option>
<option name="leaflet_maps_app.maps-plus.singleMarkerMode">1</option>
<option name="refresh.display">progressbar</option>
</viz>
</panel>
</row>
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