Using attached blueprint, when the BP is pasted in planning mode, the symmetrical connectors (both visible in the pre-paste image) behave differently. The one on the left converts to a pipe, but the one on the right remains a connector. You might think this is a matter of the direction of the pipe, but no. When the blueprint is unpaused, then the connector on the right is converted to a pipe, but the new combined entity remains unpaused.
It's an annoying issue, because the connectors are required to be there, to make the blueprint tile without issues, but they interfere with the unpausing when the BP is used stand-alone. If the whole BP is not unpaused and these pipes remain unpaused, the BP obviously won't work.



perhaps related to: https://discord.com/channels/803508556325584926/1370883840259657749/1370883840259657749
