When you typed glazed terracotta in the commands chat, it's in the wrong name. Instead of (any colored name)_glazed_terracotta, it's glazedterracotta.(color name)
MCPE-100264
Most glazed terracotta name IDs are incorrect
Resolved
Fixed
11
(Unassigned)
410528
Confirmed
Multiple
1.16.210.61 Beta, 1.16.200.51 Beta, 1.16.100.60 Beta, 1.16.100.58 Beta, 1.16.100.57 Beta, 1.16.100.56 Beta, 1.16.100.59 Beta, 1.16.201 Hotfix
1.17.11 Hotfix
Retrieved
I can confirm in 1.16.100.56.