Issue with heatmap overlays not displaying

Map visualisations (Bubble Map and Heatmap) no longer render data. The basemap displays correctly, but no data points or heat overlay appear. This occurs across multiple reports, including newly created reports, and across multiple data sources (Google Ads and GA4). Tables using the identical dimensions and metrics display data correctly. Geographic fields are correctly typed (Country, City). This appears to be a rendering regression in Looker Studio rather than a report configuration issue.