PDF Export missing Drop-Shadow-Workaround

Hi there,
currently it is not possible to add drop-shadows to symbols and shapes in Adobe Express. One work-around I found was to add a duplicate layer, put it in the background, using duotone effect in black and add blur from corrections.

However, here comes the problem:
When I export the project as PDF, this "shadow" layer is going crazy. Sometimes the paramters change in terms of blur strength, sometimes the XY coordinates vary and sometimes the whole layer disappears alltogether in the exported documents. 

It seems like there is an error wthin exporting/compiling it into the PDF framework, because JPG and PNG export works fine.

I have attached two pictures - one from a PNG export, the other failed on from a PDF screenshot. The "shadow" I am referring to is the quotation box shadow