XID_Docs not recognized as URs

[shannona]

% echo $XID_ID
ur:xid/tpsplftpsotanshdhdcxndinheaxflisnletlbntglcsatfxcwlbsbinjlnyfhayrykibbvstdtyzmrdrtkeoyaylstpsotansgylftanshfhdcxmhptlrnbdymeykswrfgmbdrowpfgayoeregdtpbwtbylwtnydktamkcenthflprltansgrhdcxfnfmdrolsrfwgtyljndlmtfriefdlksfwpjolfaocniapdbyzebyketbeeehenbnoycsfncsfglfoycsfptpsotansgtlftansgohdcxksdpzsfyhybndpbesflssfldenrpttbyaswmwmoshsplvyjpnlsnbwpeoxtptpuytansgehdcxgrwybkwdgrlkhssakiwdvsndnscyaeadmdhdiouryakgbnmebezsiydtjosocmmuoybstpsotansgmhdcxtyrnsoihfnjycygwfwrehfasvlkttlkitpmukbfmuoyapsaetkhphtutpswmdnhpatjlghwl
% echo $XID_ID_SHORT
ur:xid/hdcxndinheaxflisnletlbntglcsatfxcwlbsbinjlnyfhayrykibbvstdtyzmrdrtkehgwmfrcn

Adding the XID_ID_SHORT to an Envelope as a UR works fine:

% ENDORSEMENT=$(envelope subject type string "Endorsement: Financial API Project")
% ENDORSEMENT=$(envelope assertion add pred-obj string "endorsementTarget" ur "$XID_ID_SHORT" "$ENDORSEMENT")
% envelope format $ENDORSEMENT
"Endorsement: Financial API Project" [
    "endorsementTarget": XID(9b695f03)
]

Doing the same with XID_ID does not:

% ENDORSEMENT=$(envelope subject type string "Endorsement: Financial API Project")
% ENDORSEMENT=$(envelope assertion add pred-obj string "endorsementTarget" ur "$XID_ID" "$ENDORSEMENT") 

% envelope format $ENDORSEMENT
"Endorsement: Financial API Project" [
    "endorsementTarget": <error: the decoded CBOR value was not the expected type>
]

They're both ur:xid, they should work the same.