When using KB/M controls, the cursor is not centered whenever it becomes visible, i.e. opening an inventory interface (inventory, furnace, chest, crafting table, etc.), opening the chat window, and opening the menu. The cursor is located wherever it was the last time it was visible.
This post already exists elsewhere. https://bugs.mojang.com/browse/MCPE-15796?jql=project%20%3D%20MCPE%20AND%20issuetype%20%3D%20Bug%20AND%20resolution%20%3D%20Unresolved%20AND%20text%20~%20%22cursor%22%20ORDER%20BY%20updated%20DESC