As mentioned earlier, Currently, this is a limitation for Balance Summary in Power BI. Appreciate if you could share your valuable feedback here - https://feedback.azure.com/d365community/forum/748a4eaa-0e25-ec11-b6e6-000d3a4f07b8 that way your feedback gets conveyed to the product group and there are high possibilities that the feature gets prioritized and be added in the near future.
Reference from - https://community.powerbi.com/t5/Desktop/Azure-Cost-Management-Balance-Summary/td-p/1062550 "As an interim measure append the data in Power BI for each month so you have history for 12 months."
Hope this helps!