Sculpting tools problem
 

I'm a noob. I've created a model of a fish and I need to make some sculpting adjustments. I select my object (in Viewport or Outliner), then go to Sculpting slot in the Shelf, click on an instrument (e.g. Sculpt tool) and when I try it on the fish only small square appears instead of a cursor with selection box when I click and drag on the object (as if it wants me to select an object to work with). But when I create some new object (e.g. Sphere) in the same scene my Sculpt tool takes the shape of a brush (a small cursor circle with a big circle of brush size) and I can sculpt that sphere. Why can't I sculpt the fish then? Why doesn't Maya recognize my fish as an object? Please help!

My guess would be it's because your object is in a group and your not selecting the geo you're selecting the group open the outliner and select the geo you want to work with.

:)

i know this is an old question but i cant help but make an account just so i can tell you how i solved it since no where online says how to fix it. i had the exact issue and went searching for an answer but wasn't satisfied as their resolution is related to groups which my object does not have. make sure that all the vertices are merged together. what happened with me is that I'm trying to make a terrain pond and hills by creating 4 subdivided planes and then combining them to make one big plain (had to delete history to properly remove the groups that are created after the combining action, but that's not the point). i then merged the edges where the edge of the plains meet. however, i seem to miss on a big chunk of them preventing me from seeing the cursor and sculpting.

so in conclusion, if you don't have groups for that object and is in fact one whole mesh like mine, the issue would be the disconnected vertices that need to be merged. it will probably be hard to find where the disconnected edges or vertices are as it is a sculpt. so i would suggest that you just select all of the vertices or edges or faces and then merge. you may have to change the merging threshold.