Make sure that filters are updated. To do so, press AdGuard icon in the menu bar → Settings icon (gear) → Check for Filter updates
Open AdGuard Preferences... → Extensions and turn on AdGuard Extra.
Make sure that the necessary filters are enabled. Press AdGuard icon in the menu bar → Settings icon (gear) → Preferences → Filters. AdGuard Base filter and Language specific filters for your particular language — are necessary minimum.
If filters are in order, open Preferences... → General → Edit Allowlist... The needed website might be in that list. If so, remove it.
If the previous measures did not help, then we come into action. Open Preferences... → Assistant → find your browser and press Get the extension. Install the extension and enable it. Press the button Block ad on this website and chose the element to block.
If your browser is not in the list, then tick the checkbox Legacy Assistant. Reload the website and you will see AdGuard icon at the right bottom corner. Press on it → Block ad on this website and chose the element to block.
This should help, at least temporarily. Afterwards, press "Report this website" and follow instructions. Our developers will handle it.