After exploring a lot on your issue, I found that the tile limit is 100 for any of the Azure dashboards. As given in the above answer, there are some preview limitations existed for the preview dashboards. Reference MSDoc for the relevant information.
The dashboard preview doesn't have the full functionality of Workbooks.
Check that if there are any filters or settings applied to the query which are blocking the tile number to increase. Make sure to revisit the visualisation settings again to avoid the conflicts.
I have checked in my Azure Portal dashboard environment for different kinds of workbook and was able to keep the limit to 100 without any fail**.**
Check if the query you are trying to visualise has any restrictions or blockers added which may affect in increasing the number of tiles.
If still the issue persists, you can directly add tiles from the Tile Gallery.
Hope this helps.
If the answer is helpful, please click Accept Answer and kindly upvote it. If you have any further questions about this answer, please click Comment.