Please note, that because of issues regarding exploitative economy trading between migrated accounts, we have had to make some changes to migration allowances. Sorry for the surprise!
The additional list of currently restricted items now includes:
Rivens (All types: Melee, Rifle, Shotgun, and Pistol)
Arcanes (only ones dropped by Eidolons)
As part of this process, account items which are on this list that have already been migrated will be removed, retroactively. We are very conscientious of the new player experience for our brand-new community, and as such, we wish to keep everyone on a fair and even setting, while still allowing our migrating community to enjoy the time they have put into Warframe.
We appreciate your patience during this period, and we will be posting updates as developments occur.
I can provide some clarity here.
As it stands, those items have been removed, not just deactivated.
To give you a bit more of a background here without going too deep into specifics, this was a hard decision to make and it was not one made lightly. While it may seem like a simple matter to return or convert items, there is a lot of work in the back end that needs to go into such actions, especially when you consider cross-platforms over migrated accounts. We saw evidence of users planning to use these exploits to take advantage of new Switch players with impossible trades, as well as generating an infinite amount of copies, using items that were not obtained through playing the game as most of you have done.
The chance to migrate the account was one we decided on, because we didn't want our PC players to start from scratch, but that is tempered with the decision to already restrict some items that were covered before (such as founders items, etc). Rivens are especially hard to single out with bulk actions, due to the shifting and random nature of their unique statistics. This means that there are some very high-value, hard-to-trace items being duplicated, and as a result, the impact to the economy could not be mitigated without taking sweeping actions on Rivens as a whole.
In short, the damage had already been done, and to repair it (as well as prevent further abuse) the decision to nix Rivens on migration was made, albeit painfully.
We do not want you to lose your progress as much as possible, and it goes without saying you will still retain all of your Rivens and items on your PC account. This transfer to the Switch still grants you much of your equipment, your progress, and your standings. It was designed as a jumping point for a new experience, but we could not in good conscience allow those migrations to affect the countless newcomers to the Switch community by tilting the economy in the favor of those who have migrated - and certainly not towards those who have exploited the system to solidify that favor.
I hope you can empathize with our decision to proceed this way.