nexusgames
I repeat, I dont do nothing especial on events, and I think this is not related with your blackscreen. Anyway I do as this:
-On start of layout:
---->Create interstitial. Show:false
---->Create banner. Show:false
And when you want to show the add:
---->on banner ready. Show banner add
---->on interstitial ready. Show insterstitial add
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Which version of android build-tools are you using? (Mine is 27.0.3)
Are you getting any error messague on cmd when you run apksigner?
Have you set your system variable JAVA_HOME?
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Many users are using "Ultimate Ads" plugin. This could be another option for you