There is a few tricks & tips that I incorporate to try to ensure that the double rewards work.
These tricks & tips are NOT a guarantee that the double rewards will work..... however I have found that ads seem to fail less by doing these actions.
I completely shut down my game & restart it....not just swiping it into the background....properly fully closed down....before doing the following actions:
1️⃣ Just before clearing a game scene/mine (I leave 1-10 tiles uncleared).
2️⃣ Just before finishing a quest (this one can be a bit tricky unless you actually know what is going to trigger the end of the quest).
3️⃣ Just before claiming an Achievement.
I also wait a few seconds before clicking the double rewards button after furiously clearing the last tiles or finishing the quest to let the game catch up & finish filing all the resources into the relevant areas...patience seems to be a virtue.
Have you tried some basic TROUBLESHOOTING techniques such as:
Make sure you are running the most up-to-date versions of the game, Facebook, Google Play, browser, phone/device/PC operating systems, etc. (Depending on what you are playing through).
Try clearing your cache, cookies, history, etc (if you can do this).
You can also try uninstalling & reinstalling the game, Facebook, Google Play, browser, etc. (But ONLY do this if you have your player ID number & game progress registered with either your email address or Facebook account).
Another thing is to free up space on your phone/device/PC by deleting all unused & unnecessary apps, downloads, screenshots, files, songs, games, photos, videos, closing all browser tabs, etc.
When you are trying to install, open & play Diggys Adventure....make sure it is the ONLY application operating/running on your device at that time....so it has 100% dedicated use of your device & internet connection.
Have you recently downloaded, updated or changed any settings in your router, firewall, browser, antivirus, adaware, ransomware, pop-up blocker, cookie catcher or other security type software?
You can also try other things like:
1️⃣ Log out & log into the game/Facebook/Portal/Google Play, etc.
2️⃣ Turn your phone/device/PC off & on again.
3️⃣ Turn your internet connection/source off & on again.
4️⃣ Try using a different internet source (Wi-Fi or mobile data).
5️⃣ Try using a different browser.
6️⃣ Try putting browser into incognito/private mode.
7️⃣ Try using a different phone/device/PC.
Another option is to try playing through Facebook/Google Play/Portal instead of the mobile game application or vice versa.
Check out these forum threads...they contain some very useful information & links
Pixel has indicated that there are daily limitations on the number of ads available for mobiles & PCs
If none of these suggestions assist you....then I recommend that you contact Pixel support directly.
There are 3 different ways to contact PIXEL SUPPORT.
Remember to check your email spam/junk folder for replies
Do NOT send multiple Pixel support tickets in quick succession...otherwise their spambot might eat them
1️⃣ You can contact Pixel support directly through your game settings menu
2️⃣ You can also contact Pixel support directly through this link
Do NOT type in the white search box....scroll down to the categories written in BLUE.
3️⃣ You can also send an email to Pixel Support directly through this email address
If you contact Pixel Support directly via the email address below....you MUST include your player ID number....which can be found in your game settings menu