The message "No Overlay" relates to AIO and means that UKHO do not include AIO data for that area.
To remove the message you need to turn off the AIO layer on the ECDIS.
Note that AIO has been updated with a new version that was released in WK35/18 (30 August). To avoid duplication, the new version will not show T&P NMs where the producer nation has stated that they include them in their ENCs.
Please see the below link for information about which countries include NMs in the ENC updates and which countries are only available in AIO.
If you have installed AIO according to user manual, and you've checked the above file that AIO should be present, and still no AIO found. Please send email with coordinates and screenshot to email@example.com for further investigation.