Hi Sarah,
Thanks for using syncfusion products,
We have analyzed your query and we have prepared a sample based on your requirement. In that sample we are updating the data dynamically and according to that data, the axis formats also updated properly at our end. Sample used for testing can be find from below link,
By default, based on the data given to the chart, datetime axis will calculate the auto label format and interval type, so on dynamic update, setting labelFormat and IntervalType in sample is not recommendable. If you set value for this properties in sample, the reported issue may occur. More information the label format and interval type can be found here.
Screenshot:
If the issue is still persists from your side, kindly revert us by modify the above sample or provide your sample with replication steps which will be helpful in further analysis and provide you the solution sooner.
Thanks,
Baby.