Nami's Ebb and Flow half working

This has been an issue for the last few patches. I main support and I play Nami a lot. Recently around when Bard was released, it seemed that Nami's Ebb and Flow only works half its healing capacity for allies. When in game (Summoner's Rift or ARAM) I check how much it is supposed to heal and when I heal an ally, they get half of what they should actually be healed for. I tested this in a custom match with a bot, and it sometimes heals full and sometimes it heals half.