Rendering two separate objects, one object does not appear on screen - opengl

Question

I'm trying to create random terrain, surrounded by a skybox, which I will then apply a texture to. I have 2 shader programs running interchangeably but I can't seem to make the skybox appear on screen, whereas the terrain is rendered normally.
The terrain is essentially a grid on the x-z plane and every vertex has a y value generated by a noise algorithm. The grid is square and has a side of SIDE. I have centered the terrain by using an offset on the x and z values, equal to SIDE/2.
The skybox is a cube which also has a side SIDE, so it should fit perfectly with the grid inside it, and should be visible since the y values of the terrain's vertices are small compared to SIDE or even SIDE/2.
This is the code:
GLfloat skyboxVertices[24] = {
-HALF_SIDE, HALF_SIDE, -HALF_SIDE, //A = 1
HALF_SIDE, HALF_SIDE, -HALF_SIDE, //B = 2
HALF_SIDE, -HALF_SIDE, -HALF_SIDE, //C = 3
-HALF_SIDE, -HALF_SIDE, -HALF_SIDE, //D = 4
-HALF_SIDE, HALF_SIDE, HALF_SIDE, //E = 5
HALF_SIDE, HALF_SIDE, HALF_SIDE, //F = 6
HALF_SIDE, -HALF_SIDE, HALF_SIDE, //G = 7
-HALF_SIDE, -HALF_SIDE, HALF_SIDE //H = 8
};
//generating & binding skybox VAO
glGenVertexArrays(1, &skyboxVAO);
glBindVertexArray(skyboxVAO);
//creating & binding VBO for skybox vertices
glGenBuffers(1, &skyboxVBO);
glBindBuffer(GL_ARRAY_BUFFER, skyboxVBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(skyboxVertices),
skyboxVertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
glEnableVertexAttribArray(0);
//3 indices per triangle, 2 triangles per side, 6 sides for a cube
//for a total of 36
totalSkyboxElements = 36;
GLuint skyboxElements[36]{
0, 1, 3, 3, 2, 0, //front
4, 5, 1, 1, 0, 4, //up
4, 5, 6, 6, 7, 4, //back
7, 6, 3, 3, 2, 7, //bottom
1, 5, 6, 6, 3, 1, //right
0, 4, 7, 7, 2, 0 //left
};
//creating & binding VBO for skybox vertices
glGenBuffers(1, &skyboxElementsVBO);
glBindBuffer(GL_ARRAY_BUFFER, skyboxElementsVBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(skyboxElements),
skyboxElements, GL_STATIC_DRAW);
The code of the vertex and fragment shaders are as follows, and are compiled and linked without errors:
//vertex shader
#version 330 core
layout(location = 0) in vec3 position;
void main()
{
gl_Position = vec4(position, 1.0);
}
//fragment shader
#version 330 core
out vec4 color;
void main()
{
color = vec4(1.0, 1.0, 1.0, 1.0);
}
Finally, in the mainloop the code is as follows. shaderProgramSB refers to the skybox and shaderProgram refers to the terrain
glClear(GL_COLOR_BUFFER_BIT| GL_DEPTH_BUFFER_BIT);
glUseProgram(shaderProgramSB);
glBindVertexArray(skyboxVAO);
glDrawElements(GL_TRIANGLES, totalSkyboxElements, GL_UNSIGNED_INT, 0);
glUseProgram(shaderProgram);
glBindVertexArray(terrainVAO);
camera->update();
projectionMatrix = camera->projectionMatrix;
viewMatrix = camera->viewMatrix;
modelMatrix = glm::mat4(1.0);
MVP = projectionMatrix * viewMatrix * modelMatrix;
glUniformMatrix4fv(MVPLocation, 1, GL_FALSE, &MVP[0][0]);
glDrawElements(GL_TRIANGLES, totalElements, GL_UNSIGNED_INT, 0);
I have tried rendering the terrain first and the skybox after, but the result is always the same. Terrain rendered normally, skybox not rendered at all. I've been searching and searching but can't seem to locate the problem. Any help is greatly appreciated.