ID 485110 - Nodes using a non-standard default Blendmode trigger the Convert Layers dialog

Problem summary
Nodes using a non-standard default Blendmode trigger the Convert Layers dialog

Customer reported version
Mari 4.7v4

Customer reported platform
Multiple

Steps to reproduce

1) Extract the contents of the attached .zip file to the Mari Scripts folder

2) Launch Mari and open any project

3) Create a 'Dummy Blendmode Test Node'

4) Save and close the project

5) Reopen the project

Expected behaviour
The project should open without triggering the Convert Layers dialog

Actual behaviour
The Convert Layers dialog appears when the project is loaded

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:
Mari 4.7v4 - Windows 10 - CentOS 7.7
Mari 4.7v3 - Windows 10 - CentOS 7.7 - regression

Unable to reproduce bug in:
Mari 4.7v2 - Windows 10 - CentOS 7.7

Earliest version tested
Mari 4.7v2 - This issue doesn't appear in this version and has regressed