Just like the title said, fusion tag does not change the name of the selected monster.]
Bug reproduction steps
[I always use fusion tag to summon ‘WVXYZ-Dragon catapult cannon’. I had ‘XYZ-Dragon cannon’’ on the field and changed the name of other monster to VW with fusion tag… But I couldn’t special summon VWXZY.
I thought it was because of the fusion summon specification at the end of the card text. So I tested it with another monster ‘Shining Flare wingman’… And it didn’t work either even though it was a proper special summon with polymerization.]
Screenshot OR error code
[`I was supposed to be able to change a monster name to one from the extra deck to be used as a fusion material. But it doesn’t work]
What OS are you using