Unexpected Behaviour With MM Painting - Weird Extruder Preview Behaviour

[ImTooks]

Description of the bug

When using the 'Multimaterial painting' tool, the sliced model has lots of unexpected extrude lines which look like they would ruin the print. See below for images:

Painted model

Sliced result of painted model

Sliced cross section of painted model

Sliced result of unpainted model

Sliced cross section of unpainted model

Any help would be appreciated, I will attach the 3MF for reference. Cheers!

Project file & How to reproduce

Pikachu_BugTest.zip

Steps to reproduce:

1. Slice file

Checklist of files included above

• Project file
• Screenshot

Version of PrusaSlicer

Version 2.7.4+win64

Operating system

Windows 10 Home Version 10.0.19045 Build 19045

Printer model

Voron Trident 300 w/ ERCF

[Jan-Soustruznik]

Hello, @ImTooks , thank you for your feedback, we will try to fix in some next PrusaSlicer release. Have a nice day

[lukasmatena]

Fixed in 2.9.0-alpha1. Closing.