If you purchased the LEGO Dimensions Adventure Time Marceline Fun Pack (71285) from Toys R Us and intend to use her in the game, you may want to return it or contact LEGO Dimensions Support as there has been reports of widespread issues with the NFC chip. Basically, the tags for Marceline herself are coming up empty and it contains no data for the system to detect. I’m hearing that this issue is only affecting North America and the ones in the UK seem to be fine.
As far as I know, TT Games has not acknowledged the issue publicly but Toys R Us has issued a stop sale on the Fun Packs and has started pulling them from the floor. The link for the TRU product page has also been taken down. If you see them available for purchase, I suggest don’t buy it until the issue is fixed. For those who just collect the minifigures and have no interest in playing the LEGO Dimensions itself, that doesn’t really matter but for those who do, I suggest contacting support in the link above to see about getting a replacement tag.