Failed to go into learning mode

I swear I googled and searched through the forum. Anything similar was very old or another version. I have a vera lite, ui5 (latest version). Today I went to add another monoprice motion detector and vera sends a message that it is failing to go into learning mode. I have rebooted multiple times, took a quick backup. If I go through the process of devices, add device, option 1, next, it ultimately says it cannot go into learning mode. I will try to get a device count today if I can find the code again, but it seems odd that this just came up. I may try to exclude something and then see if it will go into learning mode. Is there anything that I can do to confirm I am at capacity? I was going on vacation and really wanted just one more motion detector. Thanks.