19Th Warframe Slot Can't Be Bought Through Foundry

[castem]

^Topic.  When I went to claim my 19th warframe, it told me that I needed to buy a warframe slot for 20 plat (as usual, since I don't pre-buy slots ahead of time).  However, this time I got an error - it said "Insufficient inventory space" or something along those lines (sorry, I didn't take a screenshot or remember the exact words).  It didn't allow me to buy the slot through the Foundry, so I went to the inventory screen and bought a warframe slot there (with no issues).

 

Note that this warframe slot purchase made the scroll bar appear on the side of my screen, which is (I think) what made this mess things up for the Foundry.

 

Steps to recreate

1.  Have 18 Warframe slots exactly (and have each of them filled).  (You shouldn't have a slider/scroll bar for the Warframe tab of your Inventory.)

2.  Build a warframe in the Foundry.

3.  When it's done building, attempt to claim the warframe.

4.  When the option to buy a slot for 20 platinum appears, try to do so.

5.  Error message appears (insufficient inventory), which prevents you from buying the warframe slot.