Docker build cannot fild related csproj files when building on Azure

General
1

my folder structure of the ASP.NET web app looks like this:

MyApp.Backend/
├── src/
│   ├── MyApp/
│   │   ├── MyApp.csproj
│   │   └── Dockerfile
│   ├── Core/
│   │   ├── MyLibrary1/
│   │   │   └── MyLibrary1.csproj
│   └── External/
│       ├── MyLibrary2/
│       │   └── MyLibrary2.csproj

So dockerfile is in the MyApp.Backend/src/MyApp/dockerfile.

Dockerfile itself looks like this (generated from both Rider and VS2022):

FROM mcr.microsoft.com/dotnet/aspnet:8.0 AS base
USER $APP_UID
WORKDIR /app
EXPOSE 8080
EXPOSE 8081

FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
ARG BUILD_CONFIGURATION=Release
WORKDIR /src
# Copy project files
COPY ["src/MyApp/MyApp.csproj", "src/MyApp/"]
COPY ["src/Core/MyLibrary1/MyLibrary1.csproj", "src/Core/MyLibrary1/"]
COPY ["src/External/MyLibrary2/MyLibrary2.csproj", "src/External/MyLibrary2/"]

# Restore NuGet packages
RUN dotnet restore "src/MyApp/MyApp.csproj"

# Copy everything else
COPY . .
WORKDIR "/src/src/MyApp"

# etc.....

No matter what I do, or how do I run it, dockerfile can never find the project files:

#9 [build  4/13] COPY [MyApp/MyApp.csproj, MyApp/]
#9 ERROR: failed to calculate checksum of ref 828adade-9126-45c5-a536-dc1f57fd1350::4yps4ixymnuqpupflyaiyicxz: "/MyApp/MyApp.csproj": not found

#10 [build  9/13] COPY [External/MyLibrary2/MyLibrary2.csproj, External/MyLibrary2/MyLibrary2.csproj/]
#10 ERROR: failed to calculate checksum of ref 828adade-9126-45c5-a536-dc1f57fd1350::4yps4ixymnuqpupflyaiyicxz: "/External/MyLibrary2/MyLibrary2.csproj": not found

#11 [build  8/13] COPY [Core/MyLibrary1/MyLibrary1.csproj, Core/MyLibrary1/]
#11 ERROR: failed to calculate checksum of ref 828adade-9126-45c5-a536-dc1f57fd1350::4yps4ixymnuqpupflyaiyicxz: "/Core/MyLibrary1/MyLibrary1.csproj": not found

I’ve tried playing around the WORKDIR command but to no avail. This is relatively standard folder structure of a microservice but docker just seems it cannot find the related csproj files.

The pipeline yaml file (part of it):

variables:
  dockerfilePath: 'MyApp.Backend/src/MyApp/Dockerfile'

    - task: Docker@2
      displayName: Build and push an image to container registry
      inputs:
        command: buildAndPush
        repository: $(imageRepository)
        dockerfile: $(dockerfilePath)
        containerRegistry: $(dockerRegistryServiceConnection)
        tags: |
          $(tag)