The "last refresh time" shown on a tile is the last tile refresh time, not the dataset refresh time. If there is no data changes on the tile, the cache for tile visuals won't be updated, so "the last refresh time" shown on the tile won't be updated. You can click the Refresh dashboard tiles to update the last refresh time for all tiles on the Dashboard.
In addition, if you need to show Last Dataset Refreshed Time on Dashboards/Reports, a good article below is for your reference.
Hey all - there is currently an issue where dashboard tiles built on datasets with Row-Level Security enabled will not load for end users. It will continue to work for those with edit permissions on the content. I believe that is causing the issues mentioned here. If anyone here is seeing the same issue on a dataset without Row-Level Security, please let us know.
The workaround in the meantime is to navigate to the report by clicking on the tile.
We are working on a fix for this as quickly as possible.
As @sirui_sun mentioned in the similar thread you provided previously, it seems to a known issue currently. Could you go to check if that is the case in your scenario?