Failure of metal parapet capping under-flashing
Though the following to be noted:
Aluband is not specified as metal capping under-flashing. It is specified as "window sealing system" only.
Aluband specification clearly states its temperature range(°C): 10 - 30, which is clearly indicating its unsuitability for metal capping underlay.
Protecto tape is specified as "waterproofing membrane under conventional metal or timber parapet caps", though "5mm packer must be used under the flashing" as stated in its specification.
The photo is showing severely melting under-flashingn under the metal capping. While it is unclear that what is the exact product used here, it is clear that they are heat sensitive and must be used strictly in accordance with relevant specifications.