This is a problem with the custom overlay view for Google Maps not beeing able to handle the amount of clusters. I've optimized it (and probably fixed it) already but I wasn't able to update the app since I was quite busy recently. After some final tests I hope to get it out this weekend though.
Btw. if there's anyone willing to volunteer to beta-test the app, just send an email to splunk at spp.at
Please try the new version and let me know if it is working as expected: