13. Where the regulatory authorities concerned cannot take a joint coordinated decision as referred to in paragraphs 8 and 10 of this Article, ACER shall decide on the solution to remove the recognised restriction and on the allocation of the investment costs to be borne by each transmission system operator for implementing the agreed solution or stating that no further action is to be pursued pursuant to paragraph 9 of this Article, in accordance with Article 6(10) of Regulation (EU) 2019/942. A decision to maintain the recognised restriction pursuant to this paragraph shall be reviewed every four years by ACER.