Force of Nature not (always) granting team size buff

I was playing a game earlier and was lucky enough to get a Gnar with Spatula. Put another Spatula on it to try to continue to build synergies (Yordles 4ever) and didn't get the team size boost.

Although I didn't grab a screenshot, I vividly remember being level 5, with Gnar on the board with FoN and having a team size limit of 5. I tried buying XP to un-bug it myself, but at level 6 (with the Gnar still on the board) I was still limited to 6 troops.

I tried removing and replacing my Gnar with FoN and couldn't get it to work. I didn't receive the team size buff that game. I have played other matches where it works fine (specifically, I'm remembering a game where I equipped Mordekaiser), just didn't work correctly in this specific match.