I had the same problem. I contacted Inductive and the problem was in the Historian DB. Somehow the tag was not unique. There were two tags with the same name in the same historian entry, or something like that. I think it was because I was copying and pasting UDTs to save time and changing the parameters inside the pasted one. I stopped doing that and nevar came up with the problema again.
HI, I've tried to add "zeroDateTimeBehavior=convertToNull;connectTimeout=120000;socketTimeout=120000;rewriteBatchedStatements=true", to change also chartZoomLevel or pointCount to -1 but I still get the same problem. I contact Inductive Automation support. It is an internal bug, affects pre-processed partitions, and causes a null pointer exception. Unfortunately there doesn't seem to be a workaround, however this has been fixed in 8.3.9. I've upgraded to 8.3.9 RC1, it works perfectly.