Strange, can't replicate it here.
Here's what I did to catch it first time: join a mp room, have another player to join so that the fight starts, then spec / fspec myself or opponent. Missing some steps here?
You can also check line 72 in data/script/system/tooltip_manager.lua file, it should be this:
lua code:
if (ws.replay_mode == 1 or ws.match_frame ~= frame or TB_MENU_MAIN_ISOPEN == 1 or ws.selected_player < 0) then
If it's different, verify game cache.