We have been using the 2nd Generation Developer Controlled Packages (https://developer.salesforce.com/docs/atlas.en-us.sfdx_dev.meta/sfdx_dev/sfdx_dev_dev2gp_plan_pkg_types_locked_unlocked.htm) in order to iterate on builds for testing our Lightning Components.
Today we ran into an issue when we tried to utilize a
design:attribute (https://developer.salesforce.com/docs/atlas.en-us.lightning.meta/lightning/components_config_for_app_builder_design_files.htm) and it worked fine in our scratch orgs.
However, when we went to upgrade the package in our target Sandbox org by doing a
sfdx force:package2:version:create and
sfdx force:package:install, the design component never appeared in the Lightning App Builder, despite being present in the Sandbox org's Developer Console.
Is this a known limitation of package upgrades? Or am I missing something?